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Summary - Entries from November 2017


Topics from November, 2017


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"I do not fear computers. I fear the lack of them."

Physics

Can sunlight provide power?»
               As we use up natural resources such ...
How do jet engines work?»
            Like rockets, jet ...
How does an aeroplane fly? »
               As an aeroplane moves though the ...
What is Greenwich Mean Time? »
               In 1884 an international ...
How do we measure time accurately?»
               After the invention of sundials, ...
How is time calculated? »
               The Earth spins on its own axis once ...
What is a sundial? »
                 Sundials are the ...
Why do we need to measure time? »
                 People have always ...
How can you lift very heavy objects without using powerful machinery? »
                 For thousands of years ...
How does a gyroscope stand up? »
                 A gyroscope is a heavy ...
What is centrifugal force? »
                   When you ...
Why is it so hard to start a heavy object moving? »
               Due to a force called inertia, an ...
Why do falling objects keep travelling faster? »
              Falling objects are subject to the force ...
What is friction? »
                 Friction is a type of ...
What stops us from falling off the Earth? »
                Gravity is the force that pulls ...
What is a force?»
                 A force pushes or ...
Can sound hurt?»
                 The loudness of ...
How can sound detect submarines?»
                        ...
What causes thunder?»
                 Thunder is produced when ...
What is the sound barrier? »
               At sea level, sound travels though ...
What is the Doppler Effect? »
               You will have noticed that as a car ...
What is an echo? »
                        ...
How many sounds can we hear? »
               Compared to other animals, the human ...
What is sound? »
               Sound is a form of vibration passing ...
What are lasers? »
              Lasers are devices that produce a narrow ...
How can light travel along a cable? »
               Although light travels only in ...
What is a spectrum? »
               When light strikes a transparent ...
How is light produced? »
               Light is given off by atoms that ...
How fast does light travel? »
               Light travels faster than anything ...
What is light? »
               Light is a form of electromagnetic ...
How does radar work? »
                 Radar works by sending ...
What is a printed circuit? »
               Any modern electrical device ...
How does radio communication work? »
               Radio signals are transmitted using ...
What are radio waves? »
               Radio waves form part of the ...
How do animal make use of magnetic forces? »
               Many animals migrate for very long ...
How can a train float in the air? »
                 Some experimental trains ...
What is an electromagnet? »
                    ...
What are magnets made of? »
                 Permanent magnets are ...
Magnetic motors »
                 One of the most ...
How does a compass work? »
               The magnetized needle of a compass ...
Which substances are magnetic? »
               Iron, steel and nickel are ...
Why do some metals stick to magnets? »
                 An ordinary magnet has ...
What is a magnetic field? »
                 The area around a ...
What is magnetism? »
                 Electrical currents are ...
What is a superconductor? »
                   When ...
What is alternating current? »
                  Electrical currents ...
How does electricity produce heat and light? »
            A good conductor such as copper has only very low ...
How do batteries work? »
               Batteries produce electricity by ...
How is electricity made? »
               Energy cannot be created. An ...
What is an insulator? »
               Some materials do not have the ...
What is Electricity? »
               Electricity powers our lights, ...
Why don’t people fall off the Earth? »
               Gravity is the force that holds us ...
Why do rainbows form? »
               Rainbows are formed when sunlight ...
What is infrared energy? »
                   Infrared ...
What are microwaves? »
               Microwaves are a form of radiation. ...
Forms of Energy»
How do we measure temperature?               ...
Where does the Earth’s energy come from? »
                 There is a basic law of ...
Forms of Energy»
What is light?                Light is a ...
Natural Properties»
  Why does my breath ‘steam’ in cold weather?       ...
Natural Properties»
What happens when a liquid boils?               ...
What is the mistral?»
            This is the name given to a wind which blows in ...
How are rocks formed?»
          Sedimentary rocks are formed from the sediment, or ...
Why do clouds have different shapes?»
               Clouds vary in shape according to ...
When does sheet lightning occur?»
               Sheet lightning usually occurs ...
What is twilight? »
          Twilight is the faint light which appears a little ...
Why do river deltas form? »
               A river winding its way down to the ...
When does a geyser occur?»
            A geyser occurs when a hot spring erupts, hurling ...
How can scientists control the weather?»
            Since the 1940s scientists have discovered ...
Why does Holland have so many windmills?»
          The large number of windmills in Holland, or The ...
When will a car engine stall?»
             A car engine will stall-that is to say, it ...
What is fire?»
           Fire is the outward sign that oxygen is combining ...
What makes a Boomerang come back?»
               It is the built-in-skew or twist in a ...
Why are convection heaters so-called?»
             Heating appliances specially designed to ...
Why do bats make high-pitched sounds?»
Bats use high-pitched sounds to find their way about. They are nocturnal animals. That is ...
When was the thermometer invented?»
    The fist practical thermometer or instrument for measuring ...
What does an X-Ray show?»
X-Rays are electromagnetic rays of very short wavelength which can penetrate matter through ...
How did science begin?»
Science began with the wish of some prehistoric man to find out about the workings of the ...
Why does iron go red when heated?»
Iron goes red when heated because its atoms radiate vibratory waves of an electromagnetic ...
How does an electric Iron work?»
       An electric iron is heated by a stream of electricity passing ...
Who sent the first radio message?»
Guglielmo Marconi is usually credited with sending the first radio message. Marconi was ...
What is a glass made from?»
Glass is made naturally from a fusion of silica (sand), soda and lime. This fusion can be ...
Where will water boil at a low temperature?»
Water will boil anywhere, but it boils at different temperature in different places. For ...
When was the first gas balloon used?»
The first gas balloon, filled with hydrogen, was released in Paris is August, 1783 by a ...
Why does an automobile have a carburetor?»
An automobile is driven by an internal combustion engine which will work properly only if ...
What is plastic?»
A plastic, in the modern sense of the word, is a synthetic or man-made material which can ...
How are mountains formed?»
The first mountains and valleys were the crust formed as a result of the cooling of the ...
Why does an astronaut need a space suit?»
A space suit enables an astronaut to survive by providing him artificially with conditions ...
Where was Morse code first used?»
The first message in Morse code was tapped out in the United States over a telegraph line from ...
What are Gamma rays? »
Gamma rays are streams of electromagnetic waves. They are given off from elements such as ...
Why is pollution a problem?»
Pollution is a problem because man, in an increasingly populated and industrialized world, ...
When does an atom split?»
An atom splits when it is struck by a neutron. The nucleus of the atom then breaks into two ...
How far can you see?»
If you stood on the shore looking across the sea to the horizon (the line appearing to ...
What is Radar?»
Radar, or radiolocation, as it was called in the early days, is the use of radio waves to ...
Where is Ursa Minor?»
      Ursa Minor is the name of a group of stars in the ...
What is a star?»
A star is a body of luminous gas, like the sun. But as stars are much farther away from the ...
When was the telephone invented?»
Alexander Graham Bell (1847-1922) invented and patented in 1876 the first telephone that ...
Why don’t Cranes topple over?»
Cranes do not topple over because their jib or booms are counter-balanced at the opposite ...
What is the Milky Way?»
The Milky Way, or Galaxy, is the whole concourse of stars and other bodies which can be ...
How was the world formed?»
In the beginning our universe was a mass of white-hot vapours and molten materials whirling ...
When does frost form?»
            Frost comes from the atmosphere when the ...
Why did the continents drift apart?»
       One of the most convincing explanations of why the ...
Where do earthquakes occur?»
      Earthquakes occur mainly in the regions of the earth where mountains ...
When was the sextant invented?»
            The sextant was invented in England in 1732 by ...
What is an anticyclone?»
The name anticyclone was first introduced by sir Francis Galton, the English meteorologist, ...
Why are horses measured in hands?»
Before man invented rulers and tae measures he often used his hands and feet to express the ...
Magnetism»
    How can a train float in the air? Some experimental trains ...
Magnetism»
Magnetic motors One of the most important uses of magnets is electric motors, which ...
Magnetism»
Is the Earth a magnet? The Earth is actually a huge magnet, with a magnetic north ...
Magnetism»
    Why do some metals stick to magnets? An ordinary magnet has ...
Magnetism»
    What is magnetism? Electrical currents are able to ...
Radio and Electronics»
What are silicon chips? A silicon chip is a tiny wafer of silicon (a semiconductor) ...
Radio and Electronics»
What is a printed circuit? Any modern electrical device requires a huge number of ...
Radio and Electronics»
What are radio waves? Radio waves form part of the electromagnetic spectrum. ...
The Changing Earth»
How do we know that the climate has changed? In more recent times, geologists ...
The Changing Earth»
    Why did the world’s climate change? The appearance of ...
The Changing Earth»
Poisonous air The Earth’s original atmosphere was very poisonous. It contained ...
The Changing Earth»
What is an Ice Age? Ice Ages were periods when large parts of the Earth’s surface ...
The Changing Earth»
  What was the Earth like when it was formed? The Earth had probably ...
Reshaping the Earth»
What is irrigation? Irrigation is a method of supplying water to crops artificially. ...
Reshaping the Earth»
What are the effects of deforestation? Many areas of tropical rainforest are burned ...
Reshaping the Earth»
  Can we push back the sea? The action of the waves continually erodes ...
Reshaping the Earth»
    What is acid rain? Rain containing dissolved acids falls to ...
Reshaping the Earth»
What is global warming? Since the late 1800s, the temperature of the Earth’s ...
Climate Extremes »
    Can sand dunes move? Sand dunes can move slowly, ...
Climate Extremes »
  What is permafrost? Permafrost is a layer of ice and frozen soil that ...
Climate Extremes »
    Where are the most extreme temperatures found? Libya and ...
Climate Extremes »
  Are there cold deserts? Antarctica is the biggest cold desert in ...
Climate Extremes »
Where is the world’s driest place? The world’s driest place is the Atacama ...
Weather »
What are ‘highs’ and ‘lows’? Air pressure varies across different parts of the ...
Weather »
  Thunderbolts A lightning strike discharges about 100 million volts of ...
Weather »
What causes mist and fog? Tiny water droplets condensing from moist air cause ...
Weather »
          What is a monsoon? ...
Weather »
    Who studies the weather? People called meteorologists ...
Volcanoes»
Why do geysers spout hot water? When water seeps through the ground and reaches ...
Volcanoes»
Volcanic bombs A major volcanic eruption can hurl boulders high into the air. These ...
Volcanoes»
What is lava? Lava is molten rock that reaches the Earth’s surface. Its temperature ...
Volcanoes»
What is a volcano? Volcanoes are openings in the Earth’s crust through which molten ...
Mountains»
  How can rocks be folded up? Most rocks are too brittle to be ...
Mountains»
Why do clouds form near mountains? Clouds form when damp air is forced upwards ...
Mountains»
    Are climbers able to breathe at high altitudes? The ...
Mountains»
    Which are the highest mountains in the world? The ...
Mountains»
      How are mountains formed? There are three ...
Fresh Water»
Can water wear away solid rock? Water itself cannot wear away rock, but tiny ...
Fresh Water»
  What is a spring? Many types of rock contain tiny holes like a ...
Fresh Water»
What is a delta? As a river reaches the sea its flow becomes slower, forming an ...
Fresh Water»
  Which is the world’s longest river? The Nile in Africa and the Amazon ...
Oceans»
    What causes the tides? Tides are caused by the gravity ...
Oceans»
  Why is the sea salty? A mixture of salty substances is washed out of ...
Day and Night»
Why are times different in other countries? Clocks in other countries need to be ...
Day and Night»
  Why do we have coloured sunsets? Coloured sunsets happen when light is ...
Day and Night»
  Why do we have day and night? As the Earth spins on its axis, the ...
Our Planet Earth»
  What are metals? Metals are one of the major groups of elements. ...
Our Planet Earth»
    What is the Earth made of? The Earth is made up of ...
Our Planet Earth»
What is inside the Earth? The Earth is not solid rock all the way through. It ...
Space Travel »
      Has any spacecraft ever left the Solar System? ...
Space Travel »
    Rocker power! All space flight depends on the use of ...
Space Travel »
    Who was the first man into space? Yuri Gagarin was the ...
Our Moon»
What does the surface of the Moon look like? The Moon’s surface is covered with a ...
Our Moon»
          What is the Moon made of? ...
Our Moon»
      What is a lunar month? For thousands of years ...
Our Moon»
        Why does the Moon shine? The ...
Our Moon»
  What is the Moon? The Moon is the Earth’s only satellite, and it ...
Small Worlds»
What happens when a meteorite hits the ground? When a large meteorite hits the ...
Small Worlds»
        What is the tail of a comet? ...
Small Worlds»
  Do other planets have moons? Apart from the Earth, most of the ...
The Solar System»
    Where is the largest known canyon? ...
The Solar System»
    Which planet is closest to the Sun? Mercury is the ...
The Stars»
  What is a black hole? ...
Stars»
  What is a star? Stars are huge balls of burning gas that are scattered ...
The Universe»
What is the Milky Way? The Milky Way is a huge mass of gas and stars that can be ...
The Universe»
  What was the Big Bang? The Big Bang is the most popular theory about the ...
INTRODUCTION – WEATHER»
An understanding of the weather is often vital to daily life – framers, for example, ...
THE WEATHER»
When we say “The Sun is shining”, we are talking about the weather. However, when we say ...
THE WIND»
Winds carry warm and cold air around the world. Knowing which way the wind is blowing is a ...
CLOUDS»
Clouds are formed from water vapour. The air collects this vapour as it passes over damp ...
RAIN AND SNOW»
  The tiny water droplets inside a cloud may bump into each other and join ...
AIR PRESSURE»
  We usually think of air as being weightless, but in fact air is quite heavy. ...
WEATHER ON THE MOVE»
Weather forecasting is partly done by looking at the movements of ‘fronts’ – regions where ...
STORMY WEATHER»
  Sometimes the weather can be extremely violent. One of the most severe ...
LOOKING AT THE CLIMATE»
The most important factor that influences the climate of a place is its distance from the ...
THE SEASONS»
    As the Earth spins on its axis, it orbits about the Sun. This means ...
RECORDING WEATHER»
  Around the world, weather stations record the type of weather every day – they ...
WEATHER FORECASTS»
Most people like to know in advance what the weather will be like. Weather forecasters often ...
MORE ABOUT CLOUDS»
      The fluffy, white clouds you see on fine, summer days ...
PLANET EARTH»
  When you look out to sea, the horizon (or skyline) seems curved. This is ...
THE EARTH’S ORIGIN»
  The Earth began over 4,600 million years ago. We believe that the Earth and ...
MOVING CONTINENTS»
The Earth’s crust is relatively thin, and is formed of large, flat pieces, called ‘plates’. ...
EARTH’S OCEANS»
The oceans cover about two-thirds of the Earth’s surface and have existed for more than ...
SPINNING EARTH»
      The Sun appears to us as if moves around the Earth. ...
CLIMATE»
Different parts of the globe have very different climates. It gets hotter as you travel ...
THE ATMOSPHERE»
        The air you breathe forms a thin layer ...
INTRODUCTION – THE SOLAR SYSTEM»
    Look at the sky on a clear night and you can see thousands of ...
WHAT IS THE SOLAR SYSTEM?»
The Solar System is made up of the Sun, nine planets, several moons (the number changes as ...
ORIGINS OF THE SOLAR SYSTEM»
Scientists think that the Sun and planets grew out of a cloud of dust and gas about 4,600 ...
THE SUN»
  The Sun keeps the planets in their orbits. Like other stars, the Sun emits ...
THE INNER PLANETS»
The inner planets – Mercury, Venus, Earth and Mars – are all made of rock. They are quite ...
THE GIANT PLANETS»
    Jupiter and Saturn are the two largest and fastest spinning planets ...
THE OUTER PLANETS»
Uranus, Neptune and Pluto are the planets furthest from the Sun. they get very little of ...
THE MOONS»
A moon is a ball of rock that orbits a planet. Mercury and Venus are the only planets ...
FORCES IN THE SOLAR SYSTEM»
    The planets travel round the Sun in nearly circular paths. So they ...
VISITORS TO THE SOLAR SYSTEM»
Occasionally we see ‘wanderers’ in our Solar System. A comet is a ball made of rock and ...
OBSERVING THE SOLAR SYSTEM»
The planets and stars are far too far away to see clearly, however good your eyesight is. ...
EXPLORING THE SOLAR SYSTEM»
Watching the Solar System from the Earth is one way of finding out about it. To learn more, ...
MORE ABOUT THE UNIVERSE»
  Life and death of a star When a star like our Sun first forms it is ...
What is solar energy?»
  The Sun covers our planet in light and warmth. A mixture of heat and light ...
Heat from the Sun»
What happens to the water in a paddling pool on a sunny day? The Sun makes it warm enough to ...
Electricity from the Sun’s energy»
    The Sun’s energy can be used to make heat and electricity. ...
Electricity from sunlight»
      There are other ways that the Sun’s energy is used ...
Packed with Solar Power»
        Solar cells make enough energy to power ...
Storing the Sun’s power»
There are times when we need a lot of electricity, and there are times when we need very little ...
Solar power in remote places»
Solar power is especially useful for people in some remote areas of the world. Here, there may ...
Solar energy - On the move»
Today we travel across the world in cars, boats and aeroplanes. Most of these vehicles use ...
Our solar world»
  Roadside telephones, parking metres, flashing road signs and lights in bus ...
Benefits of solar energy»
The sun shines across our world every day. It will continue to do so for many millions of ...
The future of solar energy»
    Scientists are looking for other ways to use solar energy ...
Alternative energy»
    Many people prefer to use energy sources that do not harm the ...
What is glass?»
      What have a window, a light bulb and a ...
What is glass made of?»
    Most of the glass that we use is made in a factory. It is made ...
Making glass»
  Each type of glass is made in a different way. A piece of very thin glass ...
Clear or cloudy glass?»
        Glass is useful because it keeps the ...
Helpful glass»
  Imagine your house without glass – it would be very dark with no windows or ...
Strong glass»
    If you knock a light bulb it will shatter into tiny pieces. ...
Glass and heat»
          Glass can keep heat inside ...
Glass for seeing»
    Do you wear glasses, or have you ever used a magnifying glass ...
Special glass»
  Have you ever wondered how your computer works? The answer is with the help ...
Beautiful glass»
    Glass is not only useful. Glass can be made into works of art. ...
Recycled glass»
      Your glass milk bottle may be made from old glass! ...
A glassy future»
  Today, some glass is mixed with other materials to make it lighter and ...
How oil is formed?»
Oil is a fossil fuel. It is made from the remains of tiny plants and animals called plankton. ...
Black gold»
    Every day millions of people use oil in some way. Yet, it is ...
Finding oil»
    Oil is very valuable. Geologists, people who study rocks, look ...
Oil Drilling deep»
    Drilling rigs are used to drill into the ground to reach oil. ...
From oil-field to refinery»
      Oil is often found in remote places. It is drilled ...
Uses for oil»
  Around 85 percent of refined oil is made into different types of fuel. This ...
Oil and the environment»
    Oil gives us energy and many other things but it also causes ...
Cleaner oil»
  Oil is being made cleaner to help protect the environment. Harmful ...
Oil Running out»
Oil took millions of years to form. Once it is used, it cannot be replaced. We are using it up ...
Saving oil»
    We can all help to save oil. If we use less oil, the oil we do ...
Oil for the future»
    Scientists are working on new ways to power the world in the ...
What is oil?»
    Oil is one of the world’s most important resources. We use oil ...
The future of natural gas»
Although new areas of gas are being found from time to time, we are using up our known supplies ...
Saving gas today»
We can’t replace natural gas but we can use less energy. Insulation and double glazing in your ...
Gas alternatives»
  Natural gas from the ground is not the only gas that we can use for fuel. ...
Will natural gas last forever?»
  We are using up natural gas supplies very quickly. One day, we will run out ...
Natural gas and safety»
    Natural gas burns easily, which makes it useful for providing ...
Natural gas and pollution»
  Each day, we use fossil fuels to drive our cars and to make electricity for ...
Unusual uses of natural gas»
    We use natural gas to heat our homes and to make electricity in ...
Using natural gas»
  Natural gas gives off lots of energy when it burns. Energy makes things ...
Transporting natural gas»
Gas can be taken from the ground and sent through a network of pipes to homes around the world. ...
Drilling for gas»
      Have you ever dug a hole in some sand or in the ...
Where do we find natural gas?»
    Natural gas forms deep under the ground or under the seabed. It ...
What is natural gas?»
Natural gas is invisible. It has no colour, shape or smell. But when gas burns, a flame ...
Important iron»
    The centre of the Earth is partly made of iron! Around the ...
Light and strong Metals»
    Many metals, such as iron and steel, are strong and heavy. They ...
Useful metals»
    You can see and touch metals used in things like drink cans and ...
Metals - Shiny and gold!»
  Gold, silver and platinum are special metals. They are used to make ...
Metals - Old to new»
Much of the metal we use has been used before. You can use metals again and again, by melting ...
Metals in the future»
We use metals every day. Our lives would be very different without metals. Scientists are ...
Metal Bend and stretch»
    Metals are strong, but they can be made into many shapes. There ...
Mixing metals»
    Some metals can be used on their own. Copper is used to make ...
Rock of metal»
      Before we can use metal and make it into useful ...
Mining for metals»
  You can find some metals in rivers or buried at the bottom of the sea. ...
Where metal comes from?»
    Most metals are found inside rocks, at the bottom of the sea ...
What are metals?»
  Metals are everywhere! You can see and touch metals in the kitchen, in the ...
The future of wind power»
      Wind power will be more important in the future ...
Arguments against wind power»
  Some people think that wind turbines spoil the landscape. They also say ...
The benefits of wind power»
  Wind is a free and endless supply of energy. Once they are built, wind ...
Local wind power»
  Wind power can be used locally to power individual houses or schools. It is ...
Who uses wind power?»
  Over 50 countries use wind power to generate electricity. Around 72 percent ...
Offshore wind power»
  Wind farms can be built offshore (out at sea). There is more wind energy at ...
Where to locate a wind farm?»
    A wind turbine needs a reliable supply of wind to generate ...
A modern wind turbine»
    The blades of a modern wind turbine can be over 40 metres long ...
How does wind power work?»
  Wind is created when energy from the Sun heats up the air around you. Of ...
Powerful wind»
      Wind energy plays an important part in the natural ...
What is wind energy?»
      Have you ever had your hat blown off by the wind? ...
What is wind?»
    Wind is the movement of air in the atmosphere from one place to ...
Changing tides»
    Twice a day, the sea moves up and down the seashore. It is high ...
The advantages of nuclear power»
  Nuclear power is made without burning fuels that release harmful gases. ...
The disadvantages of nuclear power»
    Many people worry about the safety of nuclear energy and the ...
Nuclear accidents»
    Nuclear accidents have been caused by leaking pipes and ...
Nuclear power and safety»
        There are many safeguards to make sure ...
Nuclear waste»
    No one knows what to do with waste from a nuclear reactor. ...
Nuclear energy today»
      Accidents have made nuclear power unpopular. But we ...
Future developments of Nuclear Power»
    Nuclear power may become more popular in the future. Oil and gas ...
Nuclear weapons»
    The most terrible and destructive weapons are made from nuclear ...
Other uses of nuclear energy»
  Nuclear energy has many other uses. Small amounts of radioactive materials ...
What are the uses of Nuclear energy?»
      Today, nuclear power is mainly used to make ...
What about uranium?»
    All about uranium The fuel used to produce nuclear power ...
What is nuclear power?»
    Nuclear power is a type of energy. Some countries use it to ...
Wood for the future»
  Wood is a valuable material that is used every day all over the world. ...
Wood for life»
    Trees are very important for all the life on Earth. They help ...
Wood for animals»
      Many animals use wood. Some use it as a building ...
Paper – making »
      Most of the conifer trees grown in plantations ...
Wood for medicine and food»
    Many of the foods and medicines we use come from rainforest trees ...
Wood for fuel »
    Many people all over the world use wood for burning. Wood is a ...
Wood Work»
      Wood is a very useful material and is used to make ...
Trees cutting and moving»
    After the trees are cut down they are taken away. Most logs are ...
From seed to timber»
    Most of the wood we use is specially grown in large forests. These ...
Wood close up»
      Each year a tree grows a new layer of wood. The rings ...
Wood from trees»
  The wood we use comes from two types of trees. One type is called ...
What is wood?»
      Wood is an amazing natural material. It is used ...
Plastic for the future»
  The oil we use to make plastic is running out. Oil takes millions of years ...
Recycling plastic»
      Plastic can be recycled and made into something new. ...
The problem with plastic»
      Plastic is a very useful material but it also causes ...
Plastics for health »
  Plastic can be used to keep us healthy. Hospitals use plastic because it is ...
Plastic clothes»
    Some of our clothes are made from plastic. Fabrics made from ...
Which things wrapped in plastic?»
  All wrapped ...
Bubbly Plastic»
  Plastic can be made into foam. Foam is made by blowing bubbles of gas into ...
Making things with plastic»
    There are different ways of making plastic into the shapes we need. ...
What are the different types of plastics?»
        There are hundreds of different kinds ...
How is plastic made?»
          Oil is drilled and pumped out ...
What is the history of plastic?»
               Around 150 years ago, people did not ...
What is Plastic?»
                      ...
What is a CAT scanner? »
               CAT scanner is the most modern ...
Why are there three pins in a plug? »
               You know that each electrical plug ...
How heavy loads are lifted by pulleys? »
               Pulley is one of the earliest ...
What is a Black Box? »
               Whenever any airplane gets crashed, ...
How can we use the internal heat of Earth? »
               We know that our Earth is ...
What is Ceramics? »
               The word ‘ceramics’ has its origin ...
Why does sound change continuously when a vessel is filled up with tap water? »
               It is a matter of common experience ...
What is the absolute zero? »
               It is our common practice to measure ...
What are the seas of the moon? »
               When we look towards the surface of the ...
How can you find out date with the help of stars? »
               We see a large number of stars in ...
Why is it difficult to see things immediately when we enter a dark room? »
               It is a matter of common experience ...
Why does milk spill out when boiled? »
                 When milk is heated it ...
How is flood caused? »
               If we look at the history of mankind, we ...
Why does the rising or setting sun appear bigger? »
                We know that the sun is much bigger ...
Can fresh water be obtained from the Sea? »
               We all know that sea water is salty. ...
Why do Mars appear red? »
               We know that there are nine planets ...
How do trawlers fish? »
               There is perhaps no human activity ...
Where would a ball fall when thrown inside a running train? »
               You might say that the ball would fall ...
How does an Electric Bell function? »
               When you push the button of an ...
How do electrically heated appliances work? »
Electric heaters, immersion heaters, electric irons, electric kettles, etc. are appliances ...
How does an electric fan function? »
               Electric fans have become an ...
How do a mixer and grinder work? »
               Mixer and grinder are very useful ...
How do you distinguish between force, work, energy and power? »
               In a football match it is our common ...
What is an embossing machine? »
               Embossing is the process of ...
What is Liquid Crystal Display? »
               We all have seen the digital watches ...
How does a camera’s flashlight work? »
            When someone wants to take a photograph in dim ...
What is a Hydrofoil? »
               A hydrofoil is an underwater fin which ...
How does a colour television function? »
               A television is an electronic device ...
How does a sodium lamp work? »
               Sodium lamp is used for street ...
How are acoustically sound buildings designed? »
               Acoustics is the science of the ...
What are cathode rays? »
Cathode rays are streams of electrons emitted from the negatively charged electrode or ...
What is Quantum Theory? »
               We know that light is a form of ...
What is Bernoulli’s Effect? »
               Bernoulli’s effect is an important ...
How does water pump function? »
               A water or lift pump, often called a ...
What is a lathe machine? »
            Lathe is a widely used machine in the workshops. ...
How is electricity transmitted over long distances? »
            We know that electricity is generated at power ...
What is interference of light? »
               Two centuries ago there were two ...
How does a wet Battery work? »
               A battery is a device that produces ...
How does an escalator work? »
               In modern cities or towns we ...
What is a space shuttle? »
               A space shuttle is a reusable space ...
What is a Bolometer? »
                 Bolometer is an ...
How does a motorcycle engine work? »
              We all know that a motorcycle is a ...
How does a video telephone work? »
               A video telephone is a communication ...
How does a hair drier work? »
               Sometimes, when we visit to a ...
What is Greenhouse Effect? »
               We all know that rapid ...
Does our body generate electricity? »
          We all have heard of fishes producing electric currents but ...
How is vision tested? »
               When we see an object the light ...
What is electroretinogram? »
          The recording of potential changes produced by the eye when ...
What is consciousness? »
               The word consciousness in ...
What were Marconi’s contributions to science? »
Guglielmo Marconi was born on 26th April, 1874 at Bologna in Italy. He studied Physics ...
Who was Aryabhatta? »
               Aryabhatta was a great mathematician ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    Name the space probe that was used to study the Sun. The ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    Name the first Indian satellite launching vehicle (SLV). ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    Name India’s first operational multipurpose domestic satellite. ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    Name India’s first satellite. India’s first satellite ...
History of Astronomy»
    How did Albert Einstein revolutionize the theories of ...
History of Astronomy»
        Who was Bhaskara, after whom India’s ...
History of Astronomy»
    What were the other contributions of Fredrick Herschel to ...
History of Astronomy»
      What discoveries is Jean Foucault, French Physicist ...
History of Astronomy»
      Which astronomer conclusively proved that the Sun ...
History of Astronomy»
    What was the contribution of Pierre Laplace, the French Astronomer ...
The Moon»
          What are lunar faults and ...
The Moon»
  What is known as the “Monarch of the Moon”? The crater Copernicus ...
The Moon»
      What are crater chains? Sometimes ...
The Moon»
      What are ruined lunar craters? Ruined ...
The Moon»
        Where did the first moon craft “Eagle” ...
The Moon»
How deep are lunar craters? Lunar craters can be several kilometers deep. The crater ...
The Moon»
What are the important lunar seas? The important lunar seas are: Mare ...
The Moon»
  What are the lunar seas? The lunar seas refer to the vast dark plains on ...
The Moon»
What is the lunar limb? The lunar limb is the Moon’s apparent edge as seen from the ...
The Moon»
What are the main parts of a lunar map? Basically two maps of the Moon are used, one ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
What is a solar-sail spacecraft? A solar-sail spacecraft employs a large sail just like ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
How many persons have walked on the Moon as part of the Apollo missions? Twelve ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
      When did man first land on the Moon? On 20 ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
What was the rocket used for the Apollo lunar missions? The Apollo lunar missions ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
What kind of food do astronauts eat in space? The food is frozen and dried to retain its ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
Why does an astronaut seem weightless, while orbiting the Earth in space? Actually, ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    What is a spacewalk? When astronauts go outside their ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    Can artificial gravity be provided in spacecraft or a space ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    What is a space station? A space station is a special ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    Name the first man-made object to reach another world. ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
    Name the American spacecraft that went around the Moon in ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
      Who was the first Indian to enter space? ...
ARTIFICIAL SATELLITES AND SPACE TRAVEL»
          When did the space age ...
The Stars»
What is the relationship between the size of a star and its life span? The more massive ...
The Stars»
  What are X-ray binaries? An X-ray binary system is a contact binary ...
The Stars»
        What are visual binaries? In visual ...
The Stars»
What is the Time Dilation Effect? According to Einstein’s special relativity theory, ...
The Stars»
    Can neutron stars be detected from Earth? It is thought that ...
The Stars»
      What is ‘Nemesis’? There is an unproven theory ...
The Stars»
What causes a star to become a nova? Most, if not all, novae are members of binary ...
The Stars»
    What are Lagrangian orbits? A tristar system appears to be ...
The Stars»
What is binary star system? In a binary star system, there are two stars, both ...
The Stars»
    What is a galactic Black Hole? A very compact and energetic ...
The Stars»
What is the Stationary Limit for a Black Hole? The Schwarzchild radius applies to ...
The Stars»
    What is the event horizon? Since no light can escape from a ...
The Stars»
What is a Black Hole? A Black Hole is the extremely massive remnant of a dying star. ...
The Stars»
What is a neutron star? After a supernova explosion, the collapsed core of the star ...
The Stars»
What causes the sudden collapse of a when it becomes a supernova? When the star ...
The Stars»
      How cataclysmic is a supernova explosion? When a ...
The Stars»
What are the second generation stars? First generation stars were the originally ...
The Stars»
      What is the difference between the fusion reactions up ...
The Stars»
    Do all stars evolve into red giants, then into white dwarfs and ...
The Sun»
Will the Sun cease to shine? The Sun, currently yellow, will appear red in the ...
The Sun»
What are sunspots groupings? While migrating, it can be observed that certain ...
The Sun»
What is the sunspot cycle or solar cycle? The sunspot activity on the Sun increases and ...
The Sun»
What are sunspots? Sunspots are comparatively dark areas on the Sun which appear in ...
The Sun»
  What are flares? While prominences are analogous to ordinary flames, ...
The Sun»
      What are spicules? Spicules are the eruptions ...
The Sun»
What are the disturbances that occur on the surface of the Sun due to the nuclear ...
The Sun»
Is the material in the Sun uniformly homogeneous? No. The Sun contains a central ...
The Moon»
Does the tidal effect act on the molten liquid core of the Earth? The Earth is solid ...
The Moon»
What is the tidal effect? The Earth and the Sun both exert a pull on the Moon. ...
The Moon»
What is the Moon illusion? To an observer on the Earth’s surface, the Moon looks ...
The Moon»
    What is a watery Moon? Sometimes, the Moon looks watery ...
The Moon»
    What is Earthshine? Earthshine refers to the sunlight ...
The Moon»
What is the shape of the Moon’s orbit? The orbit of the Moon around the Earth is ...
The Night Sky»
    What is the effect of the precession of the celestial sphere? ...
The Night Sky»
    What are optical doubles? Optical doubles are two stars that ...
The Night Sky»
What are the Zodiacal constellations? The Zodiacal constellations refer to twelve ...
The Night Sky»
What are constellations? Constellations are arbitrary groupings of stars. In some ...
The Earth»
    What is the exosphere? It refers to the outermost boundary ...
The Earth»
    What is Saros Period? It is a cycle of 18 years and 11.3 ...
The Earth»
    What is the Diamond Ring effect? Just before the Moon ...
The Earth»
What causes a solar eclipse? A solar eclipse occurs when the Moon comes between the ...
The Solar System»
What is the Oort cloud? Cometary periods range from a few years to even ten million ...
The Solar System»
Can collision of a planet with a large comet or asteroid occur? Large comets or ...
The Solar System»
Why was the appearance of a comet conceived to be a bad omen in ancient times? ...
The Solar System»
Is a comet always visible from the Earth? A comet normally emits no light of its own ...
The Solar System»
What is meant by the tail of a comet? When the solar wind strikes the vapour cloud ...
The Solar System»
Can a long period comet get converted into a short period one? Sometimes after ...
The Solar System»
Can a comet cease to exist? When a comet nears the Sun, a part of its material gets ...
The Solar System»
    Can comets be seen in daylight? To be seen in daylight a ...
The Universe»
What is galactic evolution? There appears to be some evidence of a possible ...
The Universe»
What are radio galaxies? They are galaxies emitting a significantly large amount of ...
The Universe»
    What is a “Nebula”? A Nebula is a cloud of gas and dust ...
The Universe»
What is the nature of the path traced by the Earth across the Universe? The path of ...
The Universe»
  To what cluster of galaxies does the Milky Way Galaxy belong? It belongs ...
The Universe»
  What portion of the universe is influenced by gravitational force? ...
The Universe»
    What is cosmology? Cosmology refers to the study of the ...
The Universe»
Will the Universe continue to expand? If the mean density of the Universe is less ...
The Universe»
How large is the Universe? The Universe apparently stretches out to an infinite ...
Astronomical Instruments»
  What are “Red Shift” and “Blue Shift” with reference to a star’s spectrum? ...
Astronomical Instruments»
    What are drive systems for modern astronomical telescopes? ...
Astronomical Instruments»
What is the altazimuth type of telescope mount? Any instrument with a magnification ...
Astronomical Instruments»
  Astronomical telescopes produce inverted images. Why are the images not ...
Astronomical Instruments»
What units do astronomers use to measure distances in the Solar System? Since ...
Astronomical Instruments»
How are photographic techniques used in astronomy? By placing a photographic film at ...
Astronomical Instruments»
    Why are instruments necessary for astronomical observations? ...
Satellites and Space Travel»
Why does a satellite constantly require orbital corrections? A satellite is ...
Satellites and Space Travel»
What are the relative merits of three-axis body stabilisation over other types of ...
Satellites and Space Travel»
  What are transfer orbits? Transfer orbit is the path pursued by a ...
Satellites and Space Travel»
What is a Sun-synchronous orbit? In a Sun-synchronous orbit, the satellite appears ...
Satellites and Space Travel»
  What are space probes? Space probes are spacecraft sent on missions ...
Satellites and Space Travel»
        What is a space shuttle? A space ...
Satellites and Space Travel»
  What are the vehicles used for space travel called? Spacecraft or ...
The Stars»
    What are Cataclysmic Variables? Two types of variable stars, ...
The Stars»
Which star other than Sun is the nearest to the Earth? The star Proxima Centauri in ...
The Stars»
What is a white dwarf? A red giant starts shrinking when its stock of hydrogen is ...
The Stars»
What happens when the hydrogen in the star is completely converted to helium? As the ...
The Stars»
What is a red giant? In the transition of the star to the red giant stage, its ...
The Stars»
      What is the main sequence? The main sequence ...
The Stars»
  How does a star form? Over a period, particles of matter from space ...
The Sun»
What is the solar wind? The solar wind is solar radiation in the form of a steady ...
The Sun»
What is the nature of radiation from the Sun? Radiation from the Sun travels in waves ...
The Sun»
What happens in a hydrogen bomb explosion? In a hydrogen bomb explosion, hydrogen ...
The Sun»
  What is the Sun made up of? Hydrogen, the most abundant element in the ...
The Sun»
How long does the Sun take to complete one revolution around the centre of the Milky ...
The Sun»
What is the distance between the Earth and the Sun? The distance between the Earth ...
The Planets»
What is albedo? Albedo refers to the proportion of incident light reflected back in all ...
The Planets»
  What is the empty focus? An ellipse has not focus but two foci, one at ...
The Planets»
What are Kepler’s Laws of Planetary Motion? Kepler’s Laws of Planetary Motion state: ...
The Planets»
How far away are the moons Phobos and Deimos from Mars. The moons are very close to ...
The Planets»
    What is the problem in observing features on the surface of ...
The Planets»
  What is the obvious snag in locating features on the gas giants Jupiter, ...
The Planets»
  Why does the Sun rise in the east and set in the west on the Earth? Does ...
The Planets»
  Do all planets have satellites? Mercury and Venus have no ...
The Planets»
Can all the planets be seen from Earth with the naked eye? Neptune and Pluto can ...
The Moon»
  How long do the Earth and the Moon take complete one orbit around their ...
The Moon»
      What are syzygy and quadrature?     ...
The Moon»
What is a New Moon? During the period in the Moon’s cycle when it appears totally ...
The Moon»
  What is libration in longitude? The orbital speed of the Moon varies, ...
The Moon»
Are all portions of the Moon visible from Earth? No. only one side of the Moon is ...
The Moon»
Does the Moon have an atmosphere? The moon may once have had an atmosphere. But ...
The Moon»
    How was the Moon formed? The Moon and the Earth are ...
The Moon»
What is the barycentre of the Earth Moon System? The barycentre of the earth Moon system ...
The Moon»
          What is Selenology? ...
The Night Sky»
  What are circumpolar stars? Circumpolar stars (also called non-setting ...
The Night Sky»
  What is the ecliptic of the celestial sphere? The ecliptic of the ...
The Night Sky»
    Does the Pole Star have any practical significance? The ...
The Night Sky»
    Why don’t the Sun and Moon twinkle? Though the Earth’s ...
The Night Sky»
    What is the horizon? The horizon is the limit of the ...
The Night Sky»
How does the Moon shine? The moon does not generate light of its own but reflects the ...
The Earth»
  What are the Solstices? During the year, the position of the Sun in ...
The Earth»
What causes the change in seasons on Earth? In the northern hemisphere, the Earth’s ...
The Earth»
What is the difference between mean local time and Indian Standard Time (IST)? The ...
The Earth»
What is the difference between mean local time and Indian Standard Time (IST)? The ...
The Earth»
      What is a civil day? A civil day is the day ...
The Earth»
What is the time difference between a lunar and a solar year? A solar year has 365 ...
The Earth»
      What are the regions or zones of the Earth? ...
The Earth»
  Can all spherical celestial bodies be imagined to have their own equator, ...
The Earth»
    What are latitudes? Latitudes are imaginary lines ...
The Earth»
      What is the difference between the geographic ...
The Earth»
    What is the speed of rotation of the Earth? The Earth ...
The Earth»
What is the shape of the Earth? The Earth is not a mere sphere but an oblate ...
The Solar System»
    What are the “canals” of Mars? In 1877 Italian ...
The Solar System»
    What is the true reason for the perturbations in the orbit of ...
The Solar System»
What are Sun Grazers and Earth Grazers? These are small number of asteroids with highly ...
The Solar System»
What are asteroids and where are they? Asteroids are small bodies orbiting the Sun. ...
The Solar System»
What are the “Morning Star” and the “Evening Star”? Mercury and Venus, due to their ...
The Solar System»
What are “Inferior” and “Superior” Planetary orbits? Mercury and Venus are said to have ...
The Solar System»
  What is an Astronomical Unit? An Astronomical unit (usually abbreviated ...
The Solar System»
What is meant by “Inner” and “Outer” Solar System? The Inner Solar System refers to ...
What are the three Laws of Motion (applicable to all bodies in the Universe) propounded by Sir Isaac Newton?»
        Newton’s Laws of Motion are: A body at rest or moving in a ...
What are the main differences between astronomy and astrology?»
In astrology (dating back to ancient times), only heavenly phenomena and movements visible to ...
The Universe»
What is meant by “Apogee” and “Pergiee”? Apogee (Aphelion with reference to solar ...
The Universe»
What are galaxies? Galaxies are clusters of stars. The Sun and the Solar System are ...
The Universe»
              ...
The Universe»
What is a natural satellite? A natural satellite is a smaller natural heavenly body ...
The Universe»
What do we mean by the Solar System? The solar system refers to the Sun and the ...
The Universe»
What is the universe? The Universe consists of everything one can cognize through ...
What is the weight of our atmosphere? »
            Our Earth is surrounded by a blanket of air from ...
What are solar flares? »
          A solar flare is defined as a sudden intense brightening ...
What are the different types of mirrors? »
           Archaeological evidences had established that mirrors ...
What is a Theodolite? »
               A theodolite is an optical ...
What is an avalanche? »
            An avalanche is a large mass of rock debris, snow, ...
What is a poison? »
            A poison is a toxic substance that is damaging to ...
What are the methods of sewage disposal? »
          Sewage is a watery mixture of all wastes that come from ...
How is cheese made? »
          Today, there are a variety of cheese made from the milk ...
Why do forward moving wheels sometimes appear turning backwards? »
            You might have observed in a movie or on a ...
What is ozone gas? »
          Ozone is a form of oxygen in which each molecule ...
What was the Stone Age? »
          The Stone Age probably began more than three million years ...
What are whispering galleries? »
          A whispering gallery is a place where a whisper is audible ...
How does a steering wheel make a car turn? »
               The word ‘steer’ means to guide and ...
What is the International Date Line? »
            The International Date Line is an imaginary line ...
What are the different types of calculators? »
          A calculator is a device that can do arithmetic calculations ...
How does a hovercraft work? »
           Hovercraft is an example of the technological ...
What is Carbon Dating? »
          Man’s curiosity has always led to the opening of new vistas ...
What is a Computer Virus? »
          Over the last few years computers have invaded almost ...
How does an airplane stay up in the air? »
               The invention of airplane is one of the ...
How do traffic lights work? »
          The growing urbanization is a direct outcome of rapid ...
What is a Cosmic Year? »
          The cosmic year is related to the motion of a galaxy. A ...
What is a boomerang? »
          Boomerang is a curved wooden missile used for hunting ...
How can we locate the North Star? »
          From the ancient times, the mariners in the Northern ...
Why is ‘pi’ such a unique number? »
          The Greek letter ‘pi’ is a unique number and is defined ...
What are the contact lenses? »
            The contact lenses are worn directly on the ...
How are different paints made? »
          Paint is a mixture of one or more coloured powders and a ...
What is a shadow? »
                        ...
What is a Range Finder? »
                    A range finder is an ...
How does a siphon work? »
            A siphon is a device used to transfer a liquid from ...
How fast do the objects fall? »
          When we throw a ball up into the air, we observe that after ...
What is the refraction of light? »
                    The ‘refraction of light’ ...
How does a parachute work? »
               A parachute is an umbrella like ...
What is a prime number? »
          Any positive integer which is greater  than one and ...
What is Electricity? »
               In ancient times, man had no idea of ...
What is a pyrometer? »
          A pyrometer is an instrument used for measuring high ...
What is solar wind? »
            The solar wind is the constant flow of charged ...
What are Novae and Supernovae? »
               Some stars that have been shining ...
How does a jet engine work? »
          ‘Every action has an equal and opposite reaction’ – Newton ...
Why does a ship float on water? »
                  It is a well-known fact that ...
What is Doppler Effect? »
               When we hear the sound of a police car ...
How do detergents perform the cleaning action? »
The word ‘detergent’ means any substance that cleans things. But today the word is usually ...
What is an ammeter? »
              The ammeter is an instrument ...
What is the science of ballistics? »
                The ballistics is a branch of mechanics ...
What is a welding torch? »
               A welding torch is a mechanical device ...
How do we measure the hardness of materials? »
            Hardness is a characteristic property of the ...
What are the different abrasives? »
          An abrasive is a substance used for grinding, cutting, ...
What is a clinometer? »
            A clinometer is an instrument used by surveyors and ...
What is electroplating? »
               Electroplating is a process of metal ...
How do satellites stay up in space? »
            A satellite is a body that moves in orbit around ...
How is sulphuric acid manufactured? »
          Sulphuric acid is called the king of acids because of ...
What is light? »
            For thousands of years many scientists groped in ...
How does a siren produce sound? »
          A siren is a device basically used to make a warning or to ...
How are metals anodized? »
               Anodizing is a process of coating a ...
How does a turbine work? »
            A turbine is a machine used to convert energy ...
How does a battery torch work? »
            A battery torch is a portable electrical ...
How does a screw jack work? »
          Almost all drivers of heavy or light vehicles always ...
What does the word bass mean? »
          Like treble, bass too describes a range of sound in ...
Why is it said that a tuning fork gives a clear example of natural frequency? »
            We know that all objects in the Universe have ...
How does a synthesizer work? »
           Synthesizers are one of the most important musical ...
Why is a mixing console an important unit? »
Mixing console is a device that used for mixing and changing the volume, and dynamics of ...
Why is it said that the telephone is an important invention? »
          The telephone is a communication tool that has become an ...
Why is it said that the telephone is the end result of many other inventions? »
             The telephone that we see around today was ...
What is meant by sound recording? »
          Sound recording and reproduction refers to the ...
Why is the introduction of the phonautograph a turning point?»
            The phonautograph was perhaps the first device in ...
Why is the phonograph an important invention? »
          Invented in 1877 by Thomas Edison, the phonograph was a ...
Why is it said that the introduction of the gramophone record changed the history of audio recording?»
          One of the most successful devices that initiated a ...
Why is it said that the CDs revolutionized sound recording?»
             A compact disc (CD) as some of you might know ...
Why is it said that a soundtrack is a necessary part of a film?»
            In its broadest sense, a soundtrack comprises ...
Why is it said that sound effects are important for a movie?»
            Imagine watching a horror film without background ...
Why is it said that sound effects are useful not only in movies, but also in video games and music?»
            You might have noticed that sound effects are ...
What is meant by the term sound-on-film? »
            Sound-on-film is a class of sound film processes ...
Why is it said that sync sounds are widely used in movies?»
               Sync sound or synchronized sound ...
Why is DTS a leader in digital sound? »
            DTS is the short form of ‘Dedicated to Sound’. It is ...
Why is the Dolby system important? »
               Roughly speaking, Dolby Digital is ...
Why is it said that SDDS is an important digital sound format? »
            Sony Dynamic Digital Sound or SDDS is a ...
Why is noise a nuisance? »
          Every day we hear different kinds of sounds. Some are ...
What is meant by the term noise pollution? »
            Noise pollution or sound pollution refers to the ...
What are the main health issues caused by noise? »
            There are many ways in which sound pollution ...
What is the effect of noise on animals? »
          Like human beings, animals too are vulnerable to loud ...
Why is it said that even underwater animals are not spared of noise pollution?»
                Almost all species on Earth are ...
What is the difference between sound waves and waves moving across water?»
           As we saw earlier, the idea of waves can be best ...
Why is it said that supersonic aircraft surpass the speed of sound?»
            Supersonic speed refers to a speed greater than ...
Why is it said that wavelength, frequency and pitch are important characteristics of sound wave? »
          Imagine yourself in a sea. You see different kinds of ...
What is meant by amplitude and Intensity?»
          Put it simple, amplitude is the height of the peaks of a ...
How do human beings make sound? »
               From the very moment of birth, we, ...
Why is it said that the ear plays a wonderful role in receiving sounds? »
            The human ear is a wonderful organ that performs ...
Why is it said that echo is one of the aspects to be taken care of?»
                The concept of echo must be ...
Why is it said that the Ancient Greeks were very familiar with acoustics?»
            The contributions made by the Ancient Greeks to ...
What is meant by the term ultrasound?»
            We have read that most humans can hear sounds ...
How is ultrasound useful for animals?»
            There are quite a lot of animals that make use of ...
Why is it said that ultrasounds are useful in SONAR?»
             Sonar is the short form for Sound ...
Which are the three main parts of the human ear? »
           The importance of ears is something we are all ...
How do sound signals reach the brain? »
            We already saw how our ears collect sounds from ...
What is meant by a treble?»
            A treble is a tone whose frequency or range is at the ...
What is an amplifier?»
            An amplifier is a device used to increase or ...
What is a loudspeaker?»
            Loudspeakers are equipments ...
Why is it said that carbon microphones were a turning point in the history of microphones?»
            Developed in the 1870s by Englishman David Edward ...
Which are some common microphones that can find around?»
            On the basis of application, microphones can be ...
Why is it said that a microphone plays a very important role in day to day sound?»
            A microphone, popularly called a mic, is a device ...
What is meant by the term sonomicrometry?»
            Sonomicrometry is a technique that makes use of ...
Why is it said that some birds can predict weather using infrasound?»
           Animals are always thought to be intelligent ...
Why is it said that some animals use infrasound for communication?»
            There are many animals that use infrasound ...
Why is it said that some animals can hear infrasounds?»
            Since time immemorial, there have been stories, ...
What is meant by Infrasound?»
            Infrasound can be defined as the low-frequency sound ...
Why is it said that ultrasound waves can be used to destroy unwanted solid deposits in our body?»
            In the case of medical ...
How is ultrasound useful in medicine?»
             Some of the most important applications of ...
How is acoustic microscopy useful?»
            Acoustic microscopy is a technology that helps in ...
Why is it said that some mammals have ears adapted for better hearing? »
          Just like humans, all forms of life in the Universe have ...
Why is it said that the hearing range of animals varies greatly? »
            As a matter of fact, no two species of animals ...
Why is it said that the hearing ability of kangaroo rats is special?»
          Kangaroo rats are unique animals that live in desert and ...
Why is it said that the barn owl can work out the direction and height of sound? »
          The barn owl is a raptor that can be spotted on all ...
Why is it said that bats use sounds to hunt? »
          Bats are fascinating animals that have many unique ...
Why is it said that birds are best known for their musical communication? »
          How many of us have seen birds that don’t make sounds? ...
Why is it said that sound is very important for animals living in water?»
               For a long time, it was believed that ...
What are the main purposes of bird communication through sound? »
          Sounds become part of a bird’s life from the very moment ...
Why is it said that whales are amazing communicators using sound? »
          Whales are in general, highly social creatures that move ...
Why is it said that humpback whales are beautiful singers?»
               The list of the best ‘singers’ among ...
Why is it said that whales use specific channels through which sounds travel? »
            For deep vibrations and low frequency sounds ...
Why is it said that howler monkeys use loud calls for communication? »
          The howler monkey is a large type of monkey that can be ...
How does a drum produce sound?»
            Drums are percussion instruments that have a ...
Why is it said that wind instruments produce sound differently?»
              Wind instruments are those musical ...
How is sound produced in string instruments? »
          String instruments are those which make notes by vibrating. ...
How does electronic music produce sound? »
            Electronic music generally refers to music ...
What is meant by acoustics? »
            Acoustics is the branch of science that deals with ...
How is the altitude of a flying airplane determined? »
            While travelling in a plane, have you ever looked ...
What is a sextant? »
          The word sextant comes from the Latin word “sextus” which ...
Which is the Land of Midnight Sun? »
          The land of the midnight sun is the popular name of the ...
What is Ionosphere? »
          The story of the discovery of the Ionosphere is very ...
Why does the Mediterranean Sea appear blue and the Atlantic Ocean green? »
            Do you know that about 3/4 of the earth’s surface ...
What is weightlessness? »
          Man experiences weightlessness in a spacecraft. Anything ...
What was the Ice Age?»
          Ice Age was those early periods of the earth’s history when ...
Why is it harder to walk uphill than downhill? »
            Generally while climbing up the stairs of a building, ...
How do deep-sea divers operate? »
           Since ancient times, man’s curiosity has led him to ...
How many stars can we count at night? »
            On a clear night, if we look up at the sky, we will ...
What are Black Holes? »
          Twentieth century astronomers have predicted dark areas in ...
When was the first artificial satellite launched? »
           A satellite is a body that orbits around another but ...
What is the Nitrogen Cycle? »
          Our atmosphere contains about 78% of nitrogen. A certain ...
How do astronauts walk in space? »
          It appears strange but true that astronauts can walk in the ...
What is magnetism? »
          Magnetism owes its name to the fact that the early ...
What is a Kaleidoscope? »
A kaleidoscope is an optical instrument used to produce symmetrical geometric patterns on ...
What are ultraviolet rays? »
          Ultraviolet rays are electromagnetic waves that cannot be ...
What are Auroras? »
          An Aurora is a beautiful pattern of light that can ...
Why are head injuries dangerous? »
In times of war, soldiers use special helmets to protect their heads. While driving a scooter, ...
Why do doctors examine the pulse? »
          When a person falls sick, the doctor often examines his ...
What is blood pressure? »
          The heart is a vital organ that pumps blood to different ...
Why do some people have a squint? »
          A squint is a physical defect in which both eyes do not ...
What is the Iron-lung machine? »
          The iron-lung machine was one of the earliest ...
What causes asthma? »
          Asthma is a chronic disease of the lungs in which a person ...
What is physiotherapy? »
          Physiotherapy is that branch of medicine which makes use ...
What are the functions of arteries and veins in our body? »
Blood must reach every cell in the body to provide it with food and oxygen, and to remove waste ...
What is electrocardiography? »
          Electrocardiography is a system of tracing graphically, the ...
Why don’t people have identical voices? »
          No two persons in the world have exactly the same voice! Do ...
What causes leprosy? »
            You must have heard of the great service, Mother ...
What do we mean by right-eyed or left-eyed people? »
We all know whether we are right-handed or left-handed. But only a few of us know whether ...
What is blood cancer or leukemia? »
          Leukemia or blood cancer is a fatal disease of the ...
What happens in our brain? »
          Normally mammals have bigger brains in relation to their ...
What is immunity? »
          Immunity is described as the ability of the body to resist ...
How do we see distant objects with binoculars? »
        If you look through binoculars, you will find distant objects ...
What is the Theory of Relativity? »
In the early nineteenth century people believed that light travelled through imaginary ...
How is an automobile’s speed measured? »
          An automobile's speed is measured by a speedometer fitted ...
How is electricity conducted through wires? »
Electricity is supplied to our homes, schools, factories and stores through copper or ...
How does an automobile engine work? »
          An automobile such as a car is an automatic self-propelled ...
What is a periscope? »
         A periscope is a very useful and interesting optical ...
How can the temperature of stars be measured? »
           We can measure our body temperature with a ...
What are the different types of thermometers? »
          A thermometer is an instrument used for measuring the ...
How does a video-tape recorder work? »
          The unique feature of a video-tape recorder (VTR) is that ...
How does a microphone work? »
          Radio and television stations make use of microphones. They ...
What is a Mass Spectrograph? »
               A mass spectrograph is an instrument ...
What are Quasars? »
In 1960, very strong radio emissions were observed by an American astronomer, Allan R. Sandage ...
How can we extinguish fires? »
          We are all aware of the damage and disaster a fire can ...
How does a polaroid camera take instant photographs? »
          The polaroid camera is also known as the ‘instant camera’ ...
Can light travel through wires? »
               We all know that electricity travels ...
What is stereophonic sound? »
          The sounds we hear with our two ears are known as ...
What is an Atomic Clock? »
          Since long, man has used clocks and watches to measure ...
How does a film projector work? »
               A projector is an optical instrument ...
What are quarks? »
            All matter is made up of small particles called ...
Can air be converted into a liquid? »
Scientists have developed techniques through which gases like nitrogen, oxygen, hydrogen, and ...
How does soap clean things? »
           Ordinary water does not remove dirt from things ...
How does an electron microscope work? »
               Optical microscopes cannot magnify ...
How does a Photostat machine work? »
            Photostat or xerography is a means of copying ...
What is solar energy? »
           Solar energy comes from the Sun to the Earth in the ...
How do we take a photograph with a camera? »
A camera is the instrument that will give us picture of a person or a scene called a ...
What is a dry cell? »
          We make use of dry cells in our torches, transistors and ...
How does an airconditioner work? »
An airconditioner is an electrically operated device used to keep houses, offices, and ...
How does a refrigerator work? »
          A refrigerator is a cabinet used for keeping food and other ...
How does a vacuum cleaner work? »
          A vacuum cleaner is an electrically operated machine which ...
What are laser beams? »
The term laser stands for “light amplification by stimulated emission of radiation”. A ...
What is a lie detector? »
          John A. Larson, a medical student from California ...
What are holograms? »
Holograms are amazing pictures that appear to have depth just like the real object. For ...
How does a fluorescent light work? »
          Man has been using artificial lights ever since he ...
What is a planetarium? »
          A planetarium is a special type of building where a ...
What are cosmic rays? »
           Cosmic rays are streams of high-energy charged ...
What are communication satellites? »
          There was a time when man used to communicate by beating ...
Who was the first man to land on the Moon? »
For many centuries man had been dreaming of space travel and exploration of ...
How does a tape recorder work? »
          A tape recorder is a machine that records sound waves into ...
What are the different forms of energy? »
          To the economist, energy is a synonym for fuel; to the ...
How is light produced by an electric bulb? »
The moment we switch on an electric bulb in a dark room in the night, the whole room is ...
How do we find direction in the sea? »
          In the beginning, when man made boats, he also used them for ...
Why does the sky appear blue? »
          Our earth is surrounded by a blanket of air, which is ...
What is electromagnetism? »
          In 1820, Hans Christian Oersted of the University of ...
What are nebulae? »
A nebula is a large cloud of gases and dust in outer space. There are two types of nebulae - ...
What is a nuclear reactor? »
               A team of scientists in Chicago, ...
How does a microscope work? »
          A microscope is an optical instrument that is used for ...
Why does iron get rusty? »
          Rust is a brownish red substance that forms on the surfaces ...
Why does thunder follow lightning? »
          During the rainy season we often see lightning in the ...
Why can’t we see stars during the day? »
          The stars become visible in the sky as soon as there is ...
What is the structure of an atom? »
               According to the ancient philosophers, ...
Can matter be converted into energy? »
        In 1905, Albert Einstein, established a relationship between mass ...
What are the wonders of X-Rays? »
          X-rays are invisible electromagnetic radiations. Their ...
What are asteroids? »
                We all know that in our solar ...
How does a thermos flask work? »
           The thermos flask is a special kind of bottle in ...
What are the different states of matter? »
          Anything that occupies space and possesses mass or ...
Why are all the heavenly bodies round? »
           The earth is round, and so are the sun and the ...
How does sound travel? »
          Whatever we hear with our ears is called ‘sound’. In ...
How is weather forecast made? »
          Weather is the day to day changes in the state of the ...
What is pasteurization? »
          Normally if fresh milk is not boiled for sometime it ...
What are infra-red radiations? »
          We know that the sunlight consists of all those colours ...
How are millions of substances made from only a few elements? »
          The number of naturally occurring stable elements on the ...
Which material does not burn in fire easily? »
          Whenever any substance is put in to fire it burns and ...
How does a pressure cooker work? »
          Pressure cooker is a modern kitchen appliance that can cook ...
What are radio waves? »
          Radio waves belong to the family of electromagnetic ...
Why do stars twinkle? »
          We see millions of stars twinkling in the sky during night. ...
How does a microwave oven work? »
          Over the years application of modern technology in the ...
Does any metal exist in a liquid state? »
               Mercury is the only metal that exists ...
What is diamond? »
          Diamond is the most precious and enduring substance in the ...
How is iron obtained from the earth? »
          Iron is found everywhere on earth. It is not only ...
Why does the leaning Tower of Pisa not falls? »
          Everybody knows that in the city of Pisa in Italy, there is ...
What is a mirage? »
          During the summer season, travellers in desert often get an ...
What causes ocean currents? »
          Most people think that the water in the oceans is still. ...
What causes tides in the sea? »
          The giant water waves which rise and fall periodically in ...
Why does bread have pores? »
          Bread is a popular food in almost all the countries of ...
How does snowfall occur? »
          Snow is formed of tiny crystals of frozen water that fall ...
How is the depth of the sea measured? »
          Before the early part of the 20th century, the only known ...
What is fire? »
          A material that burns combines quickly with oxygen in the ...
What is smoke? »
          Whenever wood, coal or some other substance burns, smoke ...
How are icebergs formed? »
          In the Southern Hemisphere, the Antarctic ice sheet ...
Why does the size of the moon appear to change? »
          On the full moon day, the moon appears like a shining disc ...
Why does wind blow? »
          We know that air is the mixture of oxygen, nitrogen, carbon ...
Why do we perspire? »
          Our body is like a furnace. The food we eat acts like fuel ...
Why do women have a sweet voice? »
          Generally the voice of women is sweeter than men. Even boys ...
How is soil formed? »
          Soil is the upper most surface layer of the earth in which ...
Why do objects appear coloured? »
          Do you know why an apple or tomato appears red, the grass ...
Which planets have satellites? »
          The heavenly bodies that revolve round the sun are called ...
How does a currency counting machine work? »
          There are thousands of banks in the world where currency ...
What is a Silicon Chip? »
          The microchip or silicon chip has completely changed the ...
What is a space suit? »
          We know that the atmosphere at the Earth’s surface ...
How is the distance of stars from the earth measured? »
          The stars which we see shining at night look very attractive ...
How can we test the purity of milk? »
             The instrument used to assess the purity of ...
What is Paging Service? »
            The 21st century would take people to a world of ...
What is Electronic Mail? »
          Electronic mail is a modern method of instant delivery of ...
How are submarines detected under the sea? »
           The main device used to detect and locate objects like ...
Why can’t we fly like birds? »
          An obvious answer to this question is, “We cannot fly like ...
What is Internet? »
          The rapid progress made in the field of Information ...
What is a Hydrogen Bomb? »
          Soon after the development of the atom bomb in 1945 ...
How are valleys formed? »
          The wide, broad plains or uneven tracts with gradual ...
What is FM transmission? »
          Over the years Frequency Modulated (FM) transmission has ...
What is Multimedia? »
          Computers have become an integral part of our lives ...
How was the Earth formed? »
               Our Earth was born around 4.6 billion ...
What is there inside the Earth? »
          Man has always been curious to know about the internal ...
How do we measure the mass of the Earth? »
          When we want to know the mass of a particular object we ...
What is the Earth’s force of gravity? »
               Anything that is dropped falls to the ...
Why don’t we feel the Earth’s motion? »
          Till a few hundred years ago, it was believed that the ...
How many kinds of climate are there? »
          Climate is the average weather experienced by an area over a ...
How seasons change? »
          We know that the Earth revolves round the Sun and also ...
What is atmosphere? »
            Atmosphere is the mass of air that envelops the ...
What is air and how is it useful for us? »
            Air envelopes the entire surface of Earth. It is ...
Does air have weight? »
               The Earth we live on is enveloped on all ...
How is the wind velocity measured? »
            Wind is moving air. Slow winds are gentle breezes. ...
How does it rain? »
We all know that clouds give us rain. Whenever the sky is cloudy, we know that it is going to ...
What is monsoon? »
          The word ‘monsoon’ is derived from the Arabic word ‘mausim’ ...
How are clouds formed? »
          The formation of clouds has always been very important ...
What are tornadoes, hurricanes and cyclones? »
             When wind moves with great speed and creates ...
How are hails formed? »
             Occasionally, you must have seen, some round ...
How is fog formed? »
          During winter mornings, sometimes we see a smoky cover on ...
What are lightning and thunder? »
          Rain is often accompanied with thunder and lightning. Even ...
How were mountains formed? »
           A mountain is a tract of land rising considerably ...
How were rivers formed? »
The word river is derived from the Latin word ‘ripa’ meaning river bank. In the ancient times, ...
How are caves formed? »
               Caves have for long been linked with ...
How are Volcanoes formed? »
            A volcano is a mountain having an opening on the ...
What causes an Earthquake? »
            Earthquakes are common occurrences. We often read ...
How are lakes formed? »
           Lakes are large masses of water formed mainly in ...
How are springs formed? »
            Sometimes a stream of water suddenly bursts out from ...
How are waterfalls formed? »
          A body of water falling down from a mountain rock is known ...
What are glaciers? »
            Glacier is a large mass of moving ice. We see ...
Why is the sea water salty? »
        Everybody knows that sea water is salty. This means that some ...
How were the oceans formed? »
         About three-fourth of the Earth’s total surface is covered ...
What is Dead Sea? »
          Dead Sea is the only sea on earth which has no plant or ...
Are there mountains inside the sea? »
          Generally, Sea Mountains are those mountains which are ...
How does a Zip Fastener work? »
Zip fastener is a fastening device in which two rows of teeth and sockets are brought ...
How does an Electric Typewriter work? »
            Electric typewriters are increasingly replacing ...
How does an Aerosol spray work? »
               Aerosols were patented in the United ...
What is radar and how does it work? »
               The word ‘radar’ is an acronym for ...
What is an Atom Bomb? »
          Atom bomb is a nuclear weapon which makes a huge explosion ...
How was the rocket developed? »
                   Today, the word ‘rocket’ ...
How was the submarine invented? »
                The submarine is a vessel which is ...
What is Superconductivity? »
              In 1911, Heike Kamerlingh Onnes, a Dutch ...
How was the telephone invented? »
             The telephone is a device by which we can ...
Who invented transistor? »
              A transistor is a tiny solid state device ...
Is there life on other planets? »
              The question whether there is life on ...
How did the universe come into existence? »
              The universe includes the Sun, Earth, solar ...
What is the Milky Way? »
            When we look at the sky in the night, a dim strip of ...
How are stars formed? »
We see innumerable stars in the sky every night. Some of the stars are very bright while ...
Why are some stars brighter than others? »
            If you look at the sky in the night you will observe ...
What is the Solar System? »
          The Solar System consists of the Sun, the nine planets and ...
What is the Sun? »
            Sun is one of the billions of stars in the sky. It ...
What are the Sun spots? »
               The most spectacular feature of the ...
What is Solar Eclipse? »
           We know that the Earth is a planet in the Solar ...
What are Meteorites? »
            When we look at the sky during the night, we ...
What is the Moon’s force of gravity? »
          All bodies of the universe attract each other. This force ...
What are Comets? »
            The shining celestial bodies with tails are called ...
What are the rings of the Saturn? »
               Saturn is the second largest planet of ...
What is Moon - the only satellite of the Earth? »
            The Moon is a heavenly body. Any heavenly body that ...
How distant are stars from us? »
            Billions of stars which we see in the sky every ...
What is the Zodiac? »
            In ancient times, when people looked up at the sky in ...
What is lunar eclipse? »
            When we stand in the sunlight, the rays of the Sun ...
What is a Compact Disc? »
            Compact disc is a new kind of disc which is recorded ...
What is the principle of an autopilot? »
Most large planes have an autopilot. This is a device operated by a computer. It will fly the ...
What is bar code? »
A bar code is computerized information encoded in a pattern of black and white stripes. The ...
What is LPG? »
         The term LPG stands for liquefied petroleum gas. LPG is ...
How does a steam iron work? »
           A hot iron smooths out creases in cloth. Most irons ...
What is the remote control of a television set? »
          The remote control is a small hand-held device used by a ...
What is automatic door operation? »
              Scientists have developed the devices by ...
What is an Alkaline Battery? »
A battery is a device that produces electricity by chemical action. A battery contains one or ...
How is synthetic rubber made? »
                  Rubber, which is in common use, ...
How are skyscrapers built? »
          Skyscrapers are tall buildings that tower in the air. The ...
What is a cellular phone? »
           Cellular telephone or radio telephone is a type of ...
What is star Television? »
          Star television is the popular name of satellite ...
How is food packed in cans? »
         Canning of food is one of the methods of food preservation. ...
How does a dish washer work? »
A dishwasher is a modern domestic appliance that cleans and dries utensils automatically. These ...
How does a washing machine work? »
          A washing machine is an electrically operated machine used ...
What are the constituents of milk? »
          Milk is white nutritious liquid produced by female mammals ...
What is Water? »
Like air, water is essential for life. Without water we cannot survive for more than a few ...
What is Uranium? »
           Uranium is a silvery, radioactive, metallic element. ...
How is silk produced? »
                   All of us are familiar ...
How do we get petrol? »
Petrol is one of the most useful products in the world. Cars, scooters, aeroplanes and various ...
What is marble? »
Marble is a kind of lime stone which is available in many colours. White marble has been in ...
Why are fireworks colourful? »
                Fireworks (crackers etc.) are used on ...
What is echo? »
            When we speak loudly in a big empty hall or in a ...
Why does the rising and setting Sun appear red? »
When the sun rises in the east, it appears like a red ball. As the day advances, its colour ...
How are the Pearls formed? »
  Pure pearls are very precious. You will be surprised to know that only a small ...
What is Plastic Surgery? »
              Plastic surgery is a branch of surgery devoted ...
What are different types of telescopes? »
            A telescope is an optical instrument used to see ...
What is Plastic? »
            Plastics do not occur naturally but are ...
What are the methods of time measurement? »
             Through the ages, man has used many methods ...
What is dry ice? »
Ice, which we generally see around us, is made by freezing the water. Water turns into ice ...
How do we see clearly with spectacles? »
              Wearing a pair of spectacles is a common ...
How do we get Wool from Sheep? »
             Warm clothes that we wear during the winter are ...
How is copper useful to us? »
              Copper is a reddish orange metal that has ...
What is helium? »
Most of the gases can be prepared in the laboratory but there are some which are found in ...
How is oxygen useful to us? »
                 Without oxygen there would have ...
How is liquid converted into vapour? »
                 It is commonly observed during ...
How is Silicon useful to us? »
Silicon is a non-metallic element. It is not found in nature in a pure form. Pure Silicon is ...
Why do hot things burn us? »
             An object is said to be hot if its ...
How is dew formed? »
                 You might have seen small drops ...
Why do watches have jewels? »
Whenever somebody purchases a wrist watch, he often enquires about the number of jewels in ...
Are the molecules of all substances in motion? »
              Every substance is made up of very tiny ...
Why is gold so costly? »
From the very ancient times man has a deep fascination for this shiny yellow coloured metal ...
How is the rainbow formed? »
            A rainbow is an arc of multi-coloured light that ...
How is dust useful to us? »
          It is a general belief that dust is very harmful to us. But ...
Why does ice float on water? »
          It is a matter of common experience that ice floats on ...
Why do we use AC supply in our homes?»
          Initially, direct current was used for power transmission. ...
Why is it said that there are two types of batteries? »
         Batteries can be broadly divided into two - primary and ...
Why is it said that a battery is the most popular source of electricity? »
          A battery is a device that stores electricity in chemical ...
Why is it said that the history of the battery is interesting? »
           Batteries are devices that have been helping mankind ...
Which is the first practical-purpose battery?»
           The Daniell cell is perhaps the first practical ...
What is meant by electromagnetism? »
Electromagnetism is a basic force of nature. It is the creation of a magnetic field from the ...
Why is the history of the electromagnetic theory interesting?»
           The history of electromagnetism cannot be complete ...
Why is it said that many of the phenomena that we witness in our daily life can explained by electro magnetic force? »
         Electromagnetism is a phenomenon that works behind almost all ...
What is an electromagnet? »
          An electromagnet is a device that can create a magnetic ...
Why is it said that the introduction of electromagnets was interesting? »
          The first recorded discovery about the relation between ...
What is meant by electromagnetic radiation? »
            There are different waves of light and energy that ...
What is electromagnetic induction? »
          In its simplest terms, electromagnetic induction can be ...
Why is it said that Thales of Miletus played a major role in the history of electricity? »
Thales of Miletus is an important figure in the history of electricity. It is said that he ...
Why is it said that the machine which produced static electricity for the first time was a turning point in history? »
          Otto von Guericke was a German scientist, and inventor who ...
Why did the relay make history? »
          The simplest definition for the relay is that it is an ...
Why the introduction of Leyden was jars a milestone in history? »
          A Leyden jar was the first device that could store electric ...
Why was the invention of the lightning rod a major breakthrough? »
                Benjamin Franklin invented the ...
Why was the introduction of the electric motor important?»
            An electric motor is a device that converts ...
Why was the introduction of the fuel cell a milestone?»
        Fuel cells are devices that generate electric current through ...
Why is it said that the amplifier and triode changed the history of electricity? »
          An electronic amplifier is a tool that can amplify or ...
Why is an ammeter important? »
         An ammeter is an instrument used to measure the flow of ...
Why is the voltmeter important equipment?»
        A voltmeter is an instrument that measures the voltage between two ...
What is a galvanometer?»
         A galvanometer is a tool that measures the flow of electric ...
What is a multimeter?»
          A multimeter is an instrument that measures the voltage, ...
Why is the ohmmeter important measuring equipment?»
        An ohmmeter is an electrical instrument used to measure resistance ...
What is an oscilloscope? »
          In simple terms, an oscilloscope is a type of equipment that ...
Why is Coulomb’s law one among the basic laws of electricity? »
Many scientists have, in the past, tried to study the features of charged particles, and the ...
Why is Georg Simon Ohm considered to be a great scientist?»
Georg Simon Ohm was German physicist who formulated the ‘Ohm’s Law’.     ...
Why is Faraday’s law important?»
          The concept of electricity cannot be complete without ...
Why is Maxwell’s equation known as the foundation of classical electromagnetism? »
       Maxwell’s equations refer to a set of four equations that describe ...
What are power stations? »
        A power station is a place where electricity is produced on a large ...
Why is it said that the history of hydroelectric power stations begins in London? »
      Hydroelectric power plants use the force of falling water to generate ...
What is meant by the ‘War of Currents’? »
        The ‘War of Currents’ was the term used to refer to the dispute ...
Why is it said that thermal power stations are common?»
A thermal power station is where heat energy is used to generate electricity. It is the ...
What makes hydroelectricity more acceptable than the electricity produced by thermal power stations?»
         As we saw earlier, hydroelectric power plants make use of ...
How is electricity produced in hydroelectric power stations? »
       As we know, it is flowing water that creates the energy required to ...
Why is osmosis and biomass much less used source of electricity generation?»
       Osmotic power is the energy that comes out of the difference in ...
How do we save electricity? »
        By now, we should all know that electric power is very precious ...
Why is an aurora considered to be the most fantastic electrical phenomenon on Earth? »
            An aurora is a display of coloured lights that ...
Why are sprites other strange electrical phenomena in nature? »
          Sprites are a natural phenomenon that is related to ...
What is St. Elmo’s fire? »
       The first account of St. Elmo’s fire surfaced a few centuries ago, ...
Why is ball lightning a strange electrical phenomenon in nature? »
     Ball lightning is an unexplained natural phenomenon that happens very ...
Why is it said that electricity can be found in some fishes? »
        Electric charge is something that is seen everywhere in the ...
Why was Benjamin Franklin’s kite experiment an important one? »
           Benjamin Franklin conducted the famous kite ...
Why is it said that Benjamin Franklin studied electricity a great deal? »
            Benjamin Franklin firmly believed that ...
Why is it said that lightning is one of the major sources of electricity?»
          Lightning could be attractive to a few and scary to others, ...
What is high voltage direct current? »
           A high voltage direct current (HVDC) is a ...
Why does voltage play a significant role in power transmission? »
         All of us have heard of the term ‘voltage’ at some point. ...
Why is it said that the earlier power transmissions used direct current? »
          Direct current, as we know, is the flow of electric charge ...
What is meant by the term DC or direct current? »
        Alternating current, as we saw, periodically reverses its ...
What is meant by AC? »
        Electric current moves often like a water stream. The only ...
What are conductors? »
          You may have heard about conductors already. They are ...
Why is it said that the secret of static electricity was known to ancient Greeks? »
          The Ancient Greeks tried to study it some two thousand ...
What is meant by static electricity? »
       Static means steady, or unmoving. In physics, static electricity ...
What is meant by electric current? »
         Usually we talk about electricity as current. But are the ...
Who identified the electron? »
          Electrons, as we know, are negatively charged subatomic ...
Why was the discovery of protons important? »
         A proton is the positively charged subatomic particle ...
Why is electric charge important?»
        Electric charge is the physical property of matter.   ...
Why is it said that the wind and tides are the best way to produce electric power?»
        The wind is a major source of renewable energy that is also useful ...
How do solar power plants work?»
As the name suggests, solar power plants use sunlight for power production. There are two ...
What is meant by the term electric power transmission? »
          Electric power transmission means the transfer of electric ...
How does electricity come to our home? »
        From the moment power is generated in a plant, it goes through ...
What is meant by overhead power lines? »
       Overhead power lines are structures for electric power transmission ...
Why is it said that transformers play a major role in electric power distribution? »
       A transformer is an electrical device that transforms electricity ...
Why is the electric meter important equipment in houses? »
         Electric meters are devices that we commonly see in houses ...
What is the measuring unit of electricity? »
Electric power is always represented in terms of watts (W) or kilowatts (kW). A thousand ...
What is meant by a short circuit?»
      Short circuit is a term we hear often, and it is something that is ...
Why is the fuse important equipment? »
          As we saw earlier, a fuse is a device that is provided ...
Why is it said the introduction of the telegraph, telephone, and loudspeaker are a culmination of electricity?»
       Telegraphy, a technology developed in the early 18th century, ...
Why is it said that electricity distribution is different in every country? »
          The electrical sector of any country in the world depends ...
Why is it said that India is a giant in the production of electricity?»
        The power sector of India is known to be one of the most ...
Why is it said that India’s grid management system is unique?»
          A power grid refers to an interconnected network for ...
Why is the use of renewable energy important? »
           There are many reasons why renewable energy is ...
Which organisms in the tropical seas are dangerous to humans? »
Most of the sea animals that can be dangerous to us are too timid to attack humans. These ...
What are mangroves?»
 Mangroves are plants that grow in the tidal zone of tropical coastal areas and are ...
Why do the sea turtles have flat armour?»
The sea turtles developed from land turtles about 200 million years ago. Their legs ...
How is a coral reef formed? »
Coral reefs consist of skeletons of small animals, called madrepores, and stacked one on top of ...
Which animals and plants live in the tropical seas? »
The tropical seas with their colourful coral reefs are one of the most conspicuous habitats of ...
How do fish and jellyfish swim? »
Fish move by flapping their fins or through wriggling movements of their body. In addition, ...
Why do pelicans have a sack in their beaks? »
Pelicans use the sack for catching fish. Interestingly, different species of pelicans use ...
How do frogs develop? »
The growth rate of the frog’s population is the same in ponds near the coast or in the ...
What are salt meadows? »
Salt meadows are area at the sea coast that are not flooded daily by sea water like the ...
Who lives along the coasts?»
Frogs croak in freshwater ponds, and a few metres ahead, fish and jellyfish swim in the salt ...
Which animals live in the Himalayas? »
The highest mountain peak of the world is Mount Everest with a height of 8850 m. Animal do ...
Are there camels in the Andes? »
There are two wild species of camels in the highlands of the South American Andes: vicunas and ...
What is the tree-line? »
The term ‘tree-line’ describes the height above which trees can no longer grow in the ...
Why do groundhogs whistle? »
Groundhogs live in widely branched burrows below the ground, but come out on the surface every ...
Are ibexes and chamois related to each other? »
Both animals have adapted to their mountain habitat. The chamois live in the upper mountain ...
Which animals and plants live in the mountains?»
Steep slopes with very little soil cover; rugged rocks, snow, and ice are the habitat in high ...
How do forest ants live? »
Most of the forest ants build hills at sunny forest edges from needles, twigs, and moss. The ...
Why do we need to protect ourselves against ticks? »
Ticks transmit dangerous diseases so we should be on the look out for them while walking in the ...
What is the difference between a stag and a deer? »
It is easy to distinguish between the large fallow deer, the red deer, and the small deer. The ...
What does a forester do? »
A forester takes care of the forest and ensures that it remains healthy. He plants new trees ...
Who lives in the forest?»
A forest is a large area of land covered with trees. Forests can be classified into many ...
Who lives in the soil? »
Along with rabbits, moles or mice that make their homes in the soil, numerous small animals ...
What is inside the oak apples?»
Although an oak apple looks like a fruit, it is actually a deformed leaf hanging by its stem ...
Why do birds migrate to the south in autumn? »
Many birds such as starlings, cranes, and swallows migrate to the south in autumn because they ...
Why do moles build hills? »
Moles spend a large part of their lives in a self-dug burrow system below the ground. The ...
How are spiders helpful? »
Many people find spiders disgusting or are afraid of them because they do not know much about ...
Which animals live in our gardens? »
A lot of activities are carried out in our gardens by animals and insects living underground, ...
What does ‘survival of the fittest’ mean? »
‘Survival of the fittest’ describes the evolution theory of Charles Darwin. In the struggle ...
Who was Charles Darwin? »
Charles Darwin (1809-1882) was a British naturalist. At a time, when people still believed that ...
Why did dinosaurs become extinct? »
Dinosaurs existed on Earth 65 million years ago. Today, the scientists believe that their ...
What is threatening the grey whales? »
The grey whale lived around 300 years ago in the Atlantic and Pacific Oceans. The giant ...
Why are elephants hunted? »
Elephants are hunted for their tusks. These are made of ivory and were used to make jewellery ...
Why do animals become extinct?»
Since the time animals have evolved species continue to become extinct. The most well-known ...
What is the difference between reptiles and amphibians? »
Amphibians such as frogs and newts are more dependent on the aquatic habitat than ...
How do fish reproduce? »
Female fish lay eggs—they spawn. The male fish eject their semen on the eggs, and thus ...
Why are there so many insects? »
Insects have the largest number of species among animals on the Earth. Out of ten different ...
What are the characteristics of mammals? »
‘Mammal’ is derived from the word ‘mammary’. The young ones of mammals suckle milk from the ...
What are species? »
Biologists have classified the animals according to their common features. Animals that share a ...
How many animal species do we have? »
There are more than 1.5 million animal species. Ranging from simple animals like sponges and ...
What does the term ‘ecological agriculture’ mean?»
A lot of things that are commonly used in commercial farming are prohibited in ecological ...
Since when do we have national parks?»
The 19th century saw the emergence of a general concern to protect the wonders of nature. The ...
What is a UNESCO natural heritage? »
The United Nations Educational, Scientific and Cultural Organization (UNESCO) is a unit of the ...
What is alternative energy?»
Energy resources are of two types. Those resources that are formed over millions of years and ...
What are the consequences of overfishing?»
Overfishing means the practice of catching fish faster than they can reproduce through natural ...
What is the greenhouse effect? »
In a greenhouse, the air gets heated up because the warm rays of the sun get trapped by the ...
What is symbiosis?»
Symbiosis is a phenomenon in which two living organisms live together in such a way that they ...
How do plants reproduce?»
Plants reproduce in a variety of ways. Many species build side shoots, from which new plants ...
How do roots help plants? »
Roots absorb water and the dissolved nutrient salts from the soil. They also store the ...
How are annual rings formed in trees? »
When trees grow, they accumulate wooden fibres around their heartwood. These fibres are bright ...
What are algae? »
Algae are plant-like living organisms. They live in the seas, freshwater or damp land areas. ...
Why should lichens be protected? »
Many lichens grow in inhospitable terrain; for instance, in the rocky highlands and cold ...
What is the difference between trees and shrubs? »
The main difference between trees and shrubs is their size. Trees are much taller than ...
What is the food chain? »
In nature, there are ‘producers’ that build the biological mass, and ‘consumers’ that eat. ...
How do camels survive long voyages in the desert?»
Camels can manage for about two weeks without drinking water because they can store up to 150 ...
What is photosynthesis? »
The chloroplast inside the green leaves of plants is the ‘workshop’ where photosynthesis takes ...
How do plants get food?»
Unlike animals, plants produce their own food and except for a few carnivorous plants, do ...
What do plants and animals need to grow? »
Almost all plants and animals need air, water, light, and nutrition to grow. Green plants use ...
Why is water important for life? »
Without liquid water there would be no life on the Earth. No other planet has liquid water, ...
Why does ice float? »
Ice floats in water because the solid form of water is lighter; it means the ice is less ...
Why is water wet?»
 The word ‘wet’ means moistening. If we dip our hand in water and take it out, it gets ...
Why do we feel cold when the body is wet? »
On a warm skin water evaporates; i.e., it is converted from liquid to gaseous state. In this ...
Why do water striders not sink? »
Water striders are very light-weight insects. Their legs are covered with millions of tiny ...
Why do container ships not sink? »
Container ships do not sink because of buoyancy. Ships made of steel are constructed in a very ...
What is hydropower?»
Water has huge power. We can feel this on our bodies when we cross a sea or river. The power we ...
How does a watermill work? »
A watermill uses a large wooden or metal wheel to generate power. It consists of many small ...
How is electricity generated by using a dam? »
Dam walls are mostly made of a material called concrete. These dams retain a large amount of ...
How energy is obtained from high and low tides?»
High and low tides come alternately, that is, one after the other. In high tides, the level of ...
How does a ferry work without an engine?»
Ferries without engines are driven by the flow of water. They are attached to a wire cable, ...
How are bubbles formed in boiling water?»
At room temperature, there is always some air dissolved in water. The colder the water, the ...
What is Heron’s ball? »
The Heron’s ball is a bellied vessel, which is partly filled with water and sealed with a ...
Who invented the first steam engine? »
James Watt is often called the inventor of the steam engine, but in reality he improved upon ...
How do paddle steamers work? »
Paddle steamers are ships that are driven by a large paddle wheel present on the side or at ...
How does a modern steam turbine work? »
In a steam turbine, hot water vapours flow from jets onto a rotor having several ...
Why do potatoes cook faster in pressure cookers than in a normal vessel? »
In a pressure cooker, the food is cooked at a higher temperature than in normal vessels. ...
What happens during burning?»
Burning is a very fast chemical reaction in which a fuel combines with oxygen, releasing heat ...
How does a candle burn? »
The secret of the candle lies in the wick. A matchstick ignites the wick. The heat of the ...
How is a fire caused? »
A fire starts with the ignition of a substance by a source that provides the necessary heat to ...
How does water extinguish fire? »
The finer the water is sprayed on a fire, the faster it evaporates. As a result, it takes away ...
How does a diesel engine work? »
Unlike a petrol engine, an air - fuel mixture is not used in a diesel engine, but instead pure ...
What are fossil fuels? »
The Latin word fossilis means ‘unearthed’ or ‘excavated’ because we need to excavate these ...
How is coal formed? »
Coal is essentially made from dead plant material. Around 300 million years ago, in the ...
How is oil discovered? »
By using acoustic or sound signals, the geologists identify the places where oil can occur on ...
How does oil reach us? »
At places where crude oil is found, huge, hollow chisels drill several hundred metres deep in ...
What is natural gas?»
Natural gas is a combustible gas or a gas that burns easily, which is formed in the same way ...
How is petrol obtained from crude oil? »
Crude oil is a mixture of different substances and must first be ‘refined’ in a refinery—it ...
How do bats orient themselves with ultrasounds? »
Bats cannot see very well. To orient themselves during their night flights, they emit ...
What is an echo? »
If you call out your name in the direction of a vertical, bare rocky wall, you will hear it ...
What are ultrasonic waves? »
Ultrasonic waves are those sound waves that are inaudible to our ears because they have a very ...
Why does a police car siren change pitch when it passes us?»
As the police car approaches us, the pitch increases, and when it moves away from us, the ...
What happens when an aircraft breaks the sound barrier? »
Jets that fly faster than sound compress the air at the front. This forms a head wave. After a ...
Why do humans see colours, but dogs do not? »
There are two types of sensory cells present on our retina: rods and cones. At twilight more ...
Why can people see better with spectacles?»
Normally, the light rays entering the eyes are bundled and refracted by the eye lens in such ...
How is a rainbow formed? »
The light coming from the sun is mainly white light. In the white light, a lot of different ...
What is refraction?»
              ...
What is light? »
The sun warms our planet, and the Earth releases a huge spectrum of radiation in the universe. ...
How do electric fuses work? »
Fuses break the electric circuit when the current becomes very strong owing to any overload. ...
Why don’t birds sitting on a high-voltage wire get a shock? »
Electricity travels from a place of high voltage to low voltage, just like water travels ...
What is the difference between direct current and alternating current? »
In direct current, electrons flow only in one direction, but in alternating current, electrons ...
What is a substation?»
European sockets provide electric current at 230 volts. Since, this voltage do not suffice to ...
What is electrical current? »
By current we mean the flow of negative charge, i.e., the flow of electrons. Metals have ...
How does electricity get to our homes?»
Electricity plants convert the energy from the raw materials of the Earth into electrical ...
What are the different types of energy resources available on the Earth? »
Along with hydropower and fossil fuels, like crude oil and coal, the Earth has other resources ...
How do geothermal power plants work?»
Geothermal power plants convert the thermal energy of the Earth into electricity. This is truly ...
Can the Earth’s heat be used for other purposes?»
Leaving aside the volcanic areas, temperature in the upper layers of the Earth’s crust varies ...
What is biogas? »
Biogas is a mixture of gases released when the remains of plants rot in the absence of oxygen. ...
How is glass manufactured? »
Glass mainly consists of lime, soda, and quartz sand. These three components are milled ...
What is porcelain made of? »
Porcelain is made of three raw materials: china clay, feldspar, and quartz. They are mixed in a ...
What is an ore? »
Metals seldom occur in their pure form in nature. They occur mostly in the form of ores, which ...
Why are diamonds expensive? »
Diamonds are very expensive because they occur at relatively few places in the world - like ...
How do windmills work? »
Windmills are machines that are driven by wind. Their blades have slightly diagonal ...
How can we use wind power?»
Years ago people used wind only for running windmills, but today we have large wind power ...
Why do large wind wheels have three rotor blades? »
When compared with the two-blade rotors, the three-blade rotors are more stable and quieter. ...
What does ‘sailing at high wind’ means? »
When we sail at ‘high wind’, we travel - as far as possible - against the wind. The wind, ...
What are ‘horse latitudes’? »
The horse latitudes are the areas in the northern and southern hemispheres of the Earth, ...
How does wind shape nature?»
Wind creates special shapes in nature. These include the elongated dunes of the sandy deserts, ...
How do aircrafts fly?»
Aircrafts need a combination of procedures to fly in the air. They need a propulsion system – ...
How does a hot-air balloon float in air? »
Air at a temperature of around 90°C is filled into the hot-air balloon. The hot air keeps the ...
How does a propeller work? »
A propeller in an aircraft scoops air, just like it scoops water in a ship. As in a wind mill, ...
How is electricity generated from solar energy? »
The sun is the source of all energy either in the form of fossil fuels or wood. After all, ...
How can we capture the heat energy of the sun?»
The easiest way to capture the heat energy of the sun is to use it to heat water. In ...
How does a solar cell work? »
The major part of all solar cells is made of silicone, which is a semi-conductor. ...
Why solar plants are not located everywhere? »
Solar collectors supply us with solar energy in the form of heat, and solar or photovoltaic ...
What is a ‘solar sail’? »
A discussion on solar sails on the television often implies the umbrella-like stretched ...
What is a magnetic sail? »
Like the ‘solar sail’, the magnetic sail is also a new possibility for using the solar energy ...
How is energy obtained from atoms?»
There are a lot of strong forces in the nuclei of atoms, which keep the particles together. ...
What forces keep the atomic nuclei together? »
Atoms are made up of a nucleus and a shell of electrons. The nucleus contains protons and ...
What is radioactivity? »
Radioactivity is a property of the atomic nuclei to decay and thereby release radiation. Many ...
What is a chain reaction? »
Chain reactions are modifications in the composition of the atomic nucleus. The nucleus of a ...
How do atomic power plants work?»
In atomic power plants - APP in short - the chain reaction of the uranium decay is allowed to ...
Why atomic power plants are considered dangerous? »
Nuclear energy is a clean energy source as it does not produce any waste gases that pollute the ...
How can we save resources for future generation?»
We need to manage our natural resources very carefully to ensure that the Earth remains in ...
What are natural resources? »
The term ‘resource’ is derived from French and means ‘tools’. Natural resources are the raw ...
Is nature the greatest treasure of the Earth? »
Nature is an immense treasure that provides us with everything we need for our survival - ...
Why do people fight for water? »
For us, water coming out of the tap is a fact that we take for granted, but for many people ...
Why are quality seals important? »
There are many types of quality seals, for example, the bio-seal for food items which are ...
What is aurora? »
Polar lights, or aurora, are bright bands of light that streak in the sky of the polar ...
What causes the Earth’s magnetic field?»
In the Earth’s core, a viscous mass containing iron moves around a solid iron core. According ...
Why does the compass needle always point to the north? »
The Earth has a huge magnetic field and all magnetic objects, such as the compass needle, get ...
How does a bottle opener work? »
A bottle opener is a simple lever. It intensifies the force with which we remove the crown cap ...
Why do we crouch down to lift a heavy box? »
The body’s centre of gravity normally lies near the belly button. When we bend forward and ...
Why is it difficult to move heavy furniture?»
Heavy furniture exerts a high pressure - force per unit area - downwards. If both the contact ...
What is a pulley?»
A pulley is a device used to lift heavy objects. It is made with a cable and a wheel of ...
Why do mountain passes have serpentine roads?»
Any work can be done in many ways. What matters is how it is done. We can climb the mountain ...
Why do astronauts wear spacesuits? »
Spacesuits allow astronauts to survive and work when they go for a ‘walk’ in space. There is a ...
Why don’t satellites fall to the Earth? »
The chairs of flying swings do not fly away because of the long chains holding them. ...
What is mass, weight, and density? »
All objects have a mass. Because of the force of attraction on the Earth, an object has a ...
Why do objects fall to the ground?»
Objects fall because the mass of the Earth attracts them. The force that pulls us towards the ...
What is a chemical reaction? »
In a chemical reaction, a chemical change takes place. The reactants lose their properties, and ...
What is a gas? »
Gas is one of the three states of matter. In a gas, the forces that bind its elements ...
What is an element? »
An element is a ‘pure substance’ consisting of atoms of the same kind. Elements cannot be ...
What is an atom?»
The term ‘atom’ comes from the Greek word atomos, meaning ‘indivisible’. Earlier, it was ...
What is the composition of air? »
Air cannot be seen, touched, or tasted, but it is much more than nothing. It is a mixture ...
What is a constellation? »
People try to find a pattern in everything they see in nature. The ancient Greeks also did ...
What would happen if there was no water on the Earth? »
Without water, there would be no animals or plants, which carry out photosynthesis and release ...
Where does the oxygen we breathe come from? »
Gaseous oxygen was created on the Earth about 3.5 billion years ago. At that time, the UV ...
How was the Earth formed? »
The Earth, along with the sun and the remaining planets of our solar system, originated ...
What makes the Earth unique? »
Unlike the other planets of our solar system, life developed into many forms on the Earth after ...
Why does the Earth rotate? »
At the beginning of the universe, there were only gas and dust particles in space. Since ...
Do the North and South Poles have seasons? »
The North and South Poles have two seasons: summer and winter. Each season lasts for six ...
Why are the days longer in summer than in winter? »
The axis of rotation of the Earth is tilted, and this can be seen clearly in a globe. ...
How fast does the Earth rotate? »
One rotation of the Earth takes one day. If at 12 noon the sun is at the highest point in the ...
How do day and night occur? »
The rotation of the Earth on its axis causes the alternation of day and night. The Earth also ...
Where does rain come from? »
Water evaporates when the sun shines on oceans, seas, or wet grounds or when wind blows over ...
Why is there an interval between lightning and thunder?»
The reason for this is that light travels faster than sound. The speed of light is 300,000 km ...
How does a thunderstorm occur? »
Accumulation of moisture in the atmosphere causes a thunderstorm. This occurs mostly in summer ...
How do tropical cyclones occur? »
When we talk about cyclones, we do not usually mean the small destructive tornadoes, but ...
How is the weather predicted?»
The weather is predicted by meteorologists—scientists who monitor weather conditions. They ...
What is Universe? »
Universe, cosmos, and space mean the same - the space all around us and what it contains as ...
How does the weather change?»
Unlike climate, weather depends on the seasons and can also change anytime. Meteorologists ...
How did the ice age occur?»
There have been many ice ages in the entire history of the Earth. During these cold phases, ...
What is the impact of ocean currents on climate?»
Hot or cold ocean currents affect the climate of the landmasses along their course. The ...
What is a trade wind? »
The trade wind is a wind that blows throughout the year in the tropics, a broad belt around ...
What is climate? »
While the weather changes every day and a hot and humid day can be followed by a rainy one, ...
Why is sand of different types?»
Sand is not a rough mixture of various rock particles, but a granular material. The ...
How are gorges formed?»
Gorges, also called ‘ravines’, ‘flumes’ or ‘canyons’, are deep, narrow valleys with sharply ...
Why is the landscape so varied?»
Different types of landscapes such as plains, wide valleys, gorges, dunes, rounded hills, and ...
How are waves formed?»
Waves are formed as a result of the constant friction between water and wind. If a wind is ...
How are icebergs made? »
The icebergs in the North Atlantic are large pieces of ice that have broken off from the ...
Why is the North Sea coast susceptible to storm tides? »
A storm tide is a natural phenomenon, and hence cannot be prevented. It happens when the normal ...
How is salt formed in the sea? »
When rain falls on the ground and seeps below it, it washes away substances from the soil and ...
What does the seabed look like? »
The seabed is that area of the Earth which has been researched the least. However, we know, ...
What is the difference between oceans and seas? »
The word ‘oceans’ implies the large water bodies of the world, namely, the Pacific, Atlantic, ...
How does a tsunami occur? »
The Japanese word ‘tsunami’ means ‘harbour wave’. It is a series of water waves caused by the ...
How do we save ourselves from earthquakes?»
Living in an earthquake-prone zone is often unavoidable. For instance, almost entire Japan ...
What damages can earthquakes cause? »
A weak earthquake— up to an intensity of 4.0 on the Richter scale—hardly causes any damage. ...
How do we measure the intensity of earthquakes? »
The intensity of an earthquake is measured by recording the tremors of the Earth’s surface with ...
Where do earthquakes occur? »
Earthquakes occur mainly at the borders of the plates, where two plates slide past each other. ...
Why does the Earth tremble sometimes?»
The moving tectonic plates, in which the uppermost layer of the Earth is divided, not only ...
Where are volcanoes found? »
Volcanoes are found primarily at the borders of the plates, where the oceanic Earth’s crust ...
Why do people live near volcanoes? »
Farmers prefer to settle near volcanoes because the soil is very fertile due to the lava ...
How can we predict volcanic eruptions? »
Because volcanoes are highly erratic, it becomes very difficult to predict volcanic eruptions. ...
When do volcanoes become dangerous? »
We can call a volcano dangerous only when it causes damage to human life. For instance, if a ...
Why do we have different types of volcanoes? »
Since the material coming out of the Earth’s core is different in different areas, the ...
How are volcanoes formed? »
        Volcanoes are natural phenomenon that ...
How were mountains formed? »
Mountains are formed in two ways. When the tectonic plates move, they collide against each ...
Who discovered the continental drift? »
This discovery is credited to the German geologist Alfred Wegener. He not only discovered that ...
How many plates does the Earth’s crust have?»
          The relatively solid ...
What is the atmosphere made up of? »
The word ‘atmosphere’ means a gaseous cover enveloping a planet. Without atmosphere life would ...
Why do we not fall off from the Earth? »
Gravity is the force of the Earth that attracts every object towards itself. From our ...
How did we discover that the Earth is round? »
About 3000 years ago people believed that the Earth was flat. But people wondered why ships ...
How do we discover what is inside the Earth? »
Caves and mines go only up to 1-2 km inside the Earth. Even the deepest wells of the world, ...
What is the internal structure of the Earth? »
Like an onion, the Earth has several layers. The outermost layer, the Earth’s crust, has an ...
What is the external structure of the Earth? »
It has been known for more than 2000 years that the Earth is round, but we were able to ...
What is Polaroid photography?»
Polaroid photography is a photographic process in which the processing of the exposed film ...
What is Quartz clock?»
It is a clock which makes use of the piezoelectric properties of quartz. A quartz crystal has ...
What is Relativity?»
The theory of relativity was put forth by Albert Einstein in two parts. The first part called ...
What is remote sensing?»
Remote sensing is a technique of collecting information about the earth’s natural resources ...
What is Scuba?»
Scuba is an acronym for Self-Contained Underwater Breathing Apparatus. It consists of a ...
What is SETI?»
SETI is an acronym for Search for Extra Terrestrial Intelligence. The possibility that ...
What is Solar wind?»
The solar wind is a stream of charged particles flowing out from the sun’s outer atmosphere or ...
What is Sonar?»
Sonar, an acronym for Sound Navigation and Ranging, is a remote sensing device used for ...
What is Sonic boom?»
Sonic boom is the loud noise created by the shock wave set up by an aircraft travelling at a ...
What are Sunspots?»
A sunspot is a relatively cooler region on the surface of the sun. For an observer on earth, ...
What is Superconductivity?»
Superconductivity is a property which enables electricity to flow through a conductor without ...
What is UFO?»
The word ‘UFO’ is an acronym for Unidentified Flying Objects. In other words, it is a flying ...
What is Ultrasound?»
Any sound of frequencies above the limit of human hearing, that is, 20,000 hertz or more, is ...
What is Virtual reality?»
Virtual reality is a term used for the reconstruction of continuously changing scenes, as one ...
What are Plastics?»
The word plastics come from the Greek word Plastikos which means ‘to shape’ or ‘able to be ...
What is Plastic money?»
Plastic money refers to the use of instruments like credit cards instead of cash in business ...
What is Photovoltaics?»
The conversion of electromagnetic radiation like sunlight into electricity through absorption ...
What is Pacemaker?»
The pacemaker is a battery operated electronic device which transmits electrical impulses to ...
What is Ozone hole?»
There is a thin layer of ozone that circles the earth at a height of 15-50 km. Its protective ...
What is Optical fibre?»
It is a thin, cylindrical cable made of glass fibre used for transmitting light signals. Light ...
What is Nuclear waste?»
In nuclear reactors a number of radioactive waste products are produced as the fuel is used ...
What is Mutation?»
A change in the structure of a gene resulting in an altered gene product, that is a ...
What is Microcomputer?»
A microcomputer is a computer which uses a microprocessor for its central processing unit. ...
What is Magnetic storm?»
It is a phenomenon caused by disturbances in the earth’s magnetic field. It gives rise to ...
What is MRI?»
MRI or the Magnetic Resonance Imaging is a technique for obtaining images of organs for ...
What is LPG?»
LPG, an acronym for Liquefied Petroleum Gas, is the most popular cooking fuel used in urban ...
What is Liquid crystal?»
Some kinds of liquid crystals can rotate the plane of polarized light and this property is ...
What is Laser?»
Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. It is a ...
What is LAN?»
LAN is the short form of Local Area Network. It allows the linking together of several ...
What is Hydroponics?»
Hydroponics is the commercial method of growing plants without using soil, by seeding them on ...
What is hologram?»
A hologram is a pattern recorded on a photographic plate or film using laser illumination ...
What is Quicksand?»
Quicksand is a bed of loose sand mixed with water. It is found in places such as river banks ...
What is Radio telescope?»
Radio telescope is a device to receive radio-waves from space. Radio-waves are emitted by a ...
What is Remote control?»
Remote control is a technique of operating a system from a distance. The operating system may ...
What is Heatstroke?»
Heatstroke is a condition when the heat regulating mechanism of the body breaks-down. ...
What is Global warming?»
Global warming is the phenomenon of a gradual overall increase in the average temperature of ...
What is geostationary satellite?»
A satellite that appears to be stationary in the sky is said to be in ‘geostationary’ ...
What are Fullerenes? »
It is a family of newly discovered, the third allotropic form of carbon, quite distinct in ...
What is Fly-by-wire?»
The term ‘Fly-by-wire’ is applied to automatic computer controlled operation of an aircraft. ...
What is Computer virus? »
A computer virus is a self-replicating computer program or a segment of code that inserts ...
What are Composites?»
Composites are materials made by combining two or more substances— one called the ...
What is Catalytic converter? »
Catalytic converter is a device, fitted onto the exhaust pipes of petrol-driven automobiles ...
What is CAT scan? »
Cat scan (Computerized Axial Tomography), sometimes also referred as CT scan, is a technique of ...
What is CAD/CAM?»
CAD and CAM are abbreviations for ‘Computer Aided Design’ and ‘Computer Aided Manufacture’ ...
What is Cable television? »
Cable television is a technique of transmitting images and sound simultaneously to many ...
What is Acupuncture?»
Acupuncture is an ancient healing art practiced by the Chinese for several thousand years. The ...
What is Compact disc? »
Compact disc is a system of recording or storing of digital audio or video information using ...
What is Computer mouse? »
Computer mouse is a device for manipulating figures on a computer screen without using a ...
What is Cryogenic engine?»
A cryogenic engine is a liquid propellant rocket motor which uses liquid oxygen and liquid ...
What is Cyclone?»
A cyclone is a low pressure area in the atmosphere in which the winds spiral inward in an ...
What is Detergents? »
Detergents are synthetic chemical salts which change the surface property of water and which ...
What is Dialysis?»
Dialysis is a process of separating dissolved substances from a solution using a semi-permeable ...
What is E-mail?»
E-mail is the short form for electronic mail, which is based on the use of computers for ...
What is El Nino? »
The El Nino is a narrow current of warm water that appears off the coast of Peru sometime in ...
What is Endoscopy?»
Endoscopy is a harmless and painless method of diagnosing diseases of any of the hollow organs ...
What is FAX? »
Fax or facsimile is a device used for transmission of a written document, photograph, map or ...
What is Black hole?»
A black hole is a fascinating and mysterious astronomical body. It is so-called because it ...
What is Atomic dock? »
Atomic clock is a device for measuring time. It makes precise measurements of time. It makes ...
What is Allergy?»
Allergy is a state of hypersensitivity acquired through the exposure to a particular substance, ...
What is AIDS?»
Acquired Immune Deficiency Syndrome (AIDS) is the most devastating and fatal disease of the ...
What is Acid rain?»
It is a phenomenon caused by industrial pollution. Natural rain always contains a small amount ...
How are Earthquakes measured? »
The severity of an earthquake can be measured either by measuring its magnitude or intensity. ...
How are Stars born? »
Stars take birth out of clouds of hydrogen, helium and dust particles present in galaxies. Due ...
How does Polish shine shoes? »
The shine of a surface depends on its smoothness. Smoother the surface, more it will reflect ...
How is Curd formed? »
Curd is formed by a chemical reaction which involves casein, the protein that occurs in milk. ...
How do Naphthalene balls keep away moths? »
The naphthalene balls used for keeping away harmful insects from damaging clothes are ...
How do Woollens keep us warm? »
Wool fibres are made of a particular protein (Keratin) which is a bad conductor of heat and as ...
How is Hail formed? »
Hail is formed in thunder clouds when ice pellets formed near the freezing level in the ...
How do Plants absorb nutrients from soil? »
Plants have special structures called root hairs for absorbing water and other nutrients from ...
How are Annular rings in plants formed? »
The annular rings or the alternating dark light circles seen in a cross section of a tree ...
How does Water rise in tall trees? »
Cells in the root hairs of plants contain dissolved sugars and salts. Water surrounding the ...
How do Igloos keep occupants warm? »
An igloo is comfortable because ice is a bad conductor of heat. It does not allow the heat ...
How is Expiry date of drugs determined? »
Most medicines, which are chemical compounds and their combinations, degrade with time. This ...
How do Seeds sprout? »
Seeds sprout when favourable temperature (15.38°C), enough oxygen and moisture are available. ...
How do Fishes survive in frozen lakes? »
Lakes which appear frozen from the top never freeze completely. Only the top layer freezes and ...
How do Animals see at night? »
No animal can see in total darkness. However, some animals are capable of making use of faint ...
How do Lizards walk on walls? »
The feet of lizards are adapted for walking on rough as well as smooth surfaces. The lizards ...
How do Spiders spin webs? »
Spiders spin webs as a means of trapping insects. They have special organs called ...
How do Bees communicate? »
Besides chemicals called pheromones, bees use a kind of dance language to tell other bees in a ...
How do Bees make honey? »
Honeybees suck nectar from a wide variety of flowers. But each bee usually keeps to a ...
How do Camels survive in deserts? »
Camels can survive for days in deserts with little food and no water due to their unique ...
How do Fish generate electricity? »
Electricity in fish is generated by the normal functions of nerves and muscles together with a ...
How do Bats fly in the dark? »
Bats navigate by making use of sounds that they emit. The way these sounds bounce off from ...
How do Chameleons change colour? »
It is not quite correct to say that a chameleon can change its colour to match coloured ...
How do Dogs track culprits? »
All dogs have keenly developed senses of smell and hearing. Dogs naturally depend on their ...
How do Animals identify their off springs? »
Many methods, not all fail-safe seem to be used by the animals in identifying their young. ...
How is Artificial insemination done? »
Artificial insemination is a method used in animal husbandry to genetically upgrade stock by ...
How is IQ measured? »
IQ, or intelligence quotient, is commonly used as a measure of an individual’s level of ...
How is Blood sugar measured? »
Sugars in our diet are converted into the glucose due to metabolism and which then goes into ...
How does Mehendi colour skin? »
Mehendi or henna leaves contain a colouring matter called lawsone. This is a dye which can bind ...
How does Paan stain mouth? »
Chewing paan without kattha will not stain the mouth. The mouth turns red on chewing paan with ...
How do Balms relieve pain? »
Pain is felt when the message reaches the brain via the nerves and the spinal cord. The ...
How is Colour printing done? »
A printed colour picture is made up of tiny dots of three primary colours — cyan, magenta, ...
How are Bifocals made? »
Bifocals are spectacles in which each lens is made in such a way that the upper and lower ...
How is Cooking oil refined? »
Vegetable oils are mixtures of chemicals called glycerides or esters of glycerides and long ...
How is Crude oil refined? »
Crude oil that comes out of an oil well is a thick, dark liquid containing a mixture of many ...
How is Cartoon films made? »
Cartoon films are made through a combination of graphic art and cinematography. The bases of ...
How are Pearls cultured? »
A pearl is a biological product produced naturally by certain oysters as a defense mechanism. ...
How are Artificial diamonds made? »
Diamond is formed in nature from graphite beneath the earth crust by the action of extreme heat ...
How are Unmanned spacecrafts controlled? »
From the moment they leave the launch pad, unmanned spacecrafts are controlled by coded radio ...
How do Trains switch tracks? »
Unlike a motor vehicle on road, a train moves on a pair of rails and its movement is ...
How do Airconditioners cool? »
        An airconditioner draws air from the ...
How do Automatic door openers work? »
Automatic door openers are usually triggered by a sensor which senses the presence of a person ...
How do ATMs work? »
An Automatic Teller Machine (ATM) performs simple banking functions such as deposits, ...
How do Spark plugs work? »
            A spark plug ...
How is Water purified? »
Water supplied to cities and towns is usually taken from rivers or lakes and contain various ...
How do Air pollution detectors work? »
Air pollution is caused by substances that are not normally part of the atmosphere's ...
How do Night-vision glasses work? »
Night vision glasses, used for seeing in the pitch dark night, use the little light available ...
How do Metal detectors work? »
Metals when present near a magnetic field create disturbance in the field. This is similar to ...
How do Common locks work? »
Locks are nothing but special latching devices in which the secured bolt is released only by ...
How do Submarines dive and surface? »
Submarines dive and resurface using the principle of buoyancy. A submarine has two walls ...
How do Parachutes work? »
The operation of the parachute is based on the simple principle of balancing two opposing ...
How do Helicopters remain stationary in mid-air? »
Unlike an aeroplane, helicopters have moving wings in the shape of spinning rotor blades. Air ...
How do Aeroplanes fly? »
Aeroplanes fly by a combination of power from the engines and lift provided by the wings. ...
How do Loudspeakers work? »
A loudspeaker is a device for converting variations of electric energy into corresponding ...
How do Gas masks work?»
Gas mask is a protective device which protects the wearer from breathing in harmful gases. As ...
How do Microwave ovens work? »
              ...
How are Musical instruments tuned? »
All musical instruments produce sound by vibration of something - a string, a membrane or a ...
How do Zippers work? »
Zipper is a fastening device which consists of two chains of metal or synthetic material, with ...
How do Lie detectors work? »
A lie detector works on the principle that a person who tells a lie is nervous and under ...
How do Hovercrafts move? »
A hovercraft is an air-cushion vehicle without wheels. It rides on a cushion of air which ...
How do Fire extinguishers work?»
Fire extinguishing agents work basically in two ways — either by cooling the burning materials ...
How do Fire alarms work?»
          Fire alarm is a safety ...
How is colour TV picture produced?»
The picture on a television screen is nothing but a pattern of glowing dots, or pixels. The ...
How do Cordless phones work?»
Cordless telephone is a wireless version of a conventional telephone. It is made up of two ...
How do Radars work?»
The word ‘radar’ stands for Radio detecting and ranging. It makes use of very short radio ...
How are Computer chips made?»
A chip is a tiny piece of silicon containing several simple electronic circuits. It is also ...
How do Spacesuits protect? »
A spacesuit is protective gear that protects an astronaut from the hostile environment of ...
How do Fireworks display colours? »
The brilliant white, sparkling yellow, glowing red and the shimmering blue colours in the ...
How does Shampoo Produce lather? »
Lather or foam is nothing but a collection of tiny soap bubbles. There is always a large ...
How do Metals corrode? »
The corrosion of metals is caused by chemical reaction. Water, salts, acids and gases — all ...
How do spiders manage without getting caught in their own web?»
A thin coating of oil on the surface of the spider's legs prevents them from sticking to ...
Can snakes hear? How do they respond to charmers’ mahudi?»
Snakes are stone deaf, yet they respond to charmers’ mahudi. Though this appears a ...
Why do we get a bulge on the skin after a mosquito bite? »
Stings of insect group animals like mosquito cause skin lesions by direct effects of the ...
When killed, some mosquitoes bleed and some do not. Why?»
 There are more than 1,200 species of mosquitoes but all of them do not feed on the ...
How do the large marine mammals manage to sleep without drowning? »
Some sleep out of the water, and some may not sleep at all. The furred or hairy aquatic mammals ...
How does a firefly emit light?»
    Firefly also known as lightning bug is the common name for about 100 species ...
Why do we blink our eyes? »
 The object of blinking of our eyelids is to keep the front of the eyeball clean. ...
With its small body mass, how does a monarch butterfly obtain enough energy to migrate 1,800 miles? »
                  ...
Why do snakes move in a zigzag manner? »
The snakes are the only vertebrates which have efficiently overcome the handicap of absence ...
Why does the light of firefly twinkle while that of glow-worm remains constant?»
            Fireflies are not really flies and glow ...
How do ants go in a line?»
     Ants are social insects. Many ant species go out of their nests in groups ...
How do ants manage to float on water?»
            Ants manage to float on water due to an ...
Ants do not get hurt when they fall. Why? »
            The fall of a body is controlled mainly by ...
How do ants find their way to hidden sweets?»
            Antennae, the two hair-like structures on ...
Why do birds never fall off their perches when sleeping? Do they, in fact, sleep? »
                    ...
Why do the eyes of some animals glow in the dark? »
The truth is that the glow is only the reflection of light from some other source. The ...
How do honey bees find their way back to their hives?»
            Bees live in colonies called hives. Each ...
Why do runners run in anti-clockwise direction? »
            As the heart is on the left side, for ...
What is the difference between hair and fur?»
  The difference between mammalian hair and fur is chiefly one of arrangement, not ...
Why are some insects attracted towards light?»
                  ...
How do insects enter and live inside mangoes?»
Adult females (about 6 mm long) of the mango nut weevil Sternochetus mangiferae Fabr puncture ...
Eagles do not flap their wings often, yet fly for long. How? »
            Eagles adopt an energy-saving flight mode ...
Why do our arms move to and fro when we walk? »
To keep our torsos stable and conserve energy, we swing our arms backwards and forwards ...
How do birds navigate home after long journeys? »
                  ...
It is true that a red flag agitates a bull? »
    It is generally believed that anything red makes a bull angry and causes it to ...
How do trees reduce air pollution?»
            Plants can prevent pollution of ...
Why do drops of lemon create white spots on the floor? »
                  ...
Why does the lotus leaf not get wet? »
            Lotus leaf does not get wet due to our ...
Could you ever see an eclipse of the Moon in daylight? »
Yes, though only for a few minutes, and only if the eclipse is occurring just as the Moon is ...
With what materials are Saturn's rings made of? »
The rings around Saturn were first identified by astronomer Galileo Galilei in 1610. It ...
Why does the Moon look silvery at night?»
              ...
Why do we always see only one side of the Moon?»
              ...
Why do the Sun and Moon appear many times larger at the horizon?»
The angular diameter of the sun and moon is about half a degree each. The celestial objects ...
Why should not the solar eclipse be viewed with naked eye?»
            One should ...
How fast is the Earth moving through space?»
The Earth is speeding like a top and like a merry-go-round horse on a carousel that is itself ...
If eclipses occur when the Sun, the Moon and the Earth lie on a straight line, why do they not occur on every new moon and full moon day? »
The eclipses of the Sun and the Moon occur during new moon and full moon respectively. A ...
What is a blue Moon?»
                ...
Why only stars blink and not planets?»
                ...
Why is it that the earliest sunrise and latest sunset do not coincide with the longest day of the year?»
                ...
Does the Sun rotate?»
Yes, the sun too rotates about its axis. But unlike the earth, which has rotation period ...
Why are the orbits of the Sun’s planets arranged in a more-or-less flat plane?»
            The planets are believed by many ...
Why does a steel ball pitch higher than a rubber ball? »
It is a scientific fact that the height to which any object bounces depends on its ...
How is information stored in audio and video tapes?»
Information is stored in audio/video tapes by magnetizing them. These tapes are actually ...
What is the origin of gravity?»
For a long time people have wondered what makes the planets go round the Sun and why ...
What is brake horse power (BHP)? How is it different from the horse power (HP)?»
              ...
We are all familiar with the popping ears associated with takeoff and landing in an aero plane. This is caused by changes in pressure, but because the aircraft cabin is artificially pressurized, why i»
For reasons of fuel economy, large civil transport aircraft have to fly at altitudes far in ...
Why does a spinning top reverse its direction of rotation towards the end? »
A spinning top process (or rotate) about its central axis due to the lateral forces given ...
While light from a candle illuminates a room, the gas (LPG) flame does not. At the same time the gas stoves help cook faster. Can anyone explain? »
Combustion (burning of fuel) can be classified into two: complete and incomplete. ...
What is the difference between hydrogen and an atom bomb?»
              An ...
Why does boiling milk overflow but boiling water does not?»
            The major component of milk is water ...
How do hearing aids work?»
 Hearing aid is an electronic device used by those who are hard of hearing, to ...
What is Global Positioning System (GPS) and how does it work?»
GPS is a system which shows the exact position on the earth, anytime in any weather and ...
Why does not sound travel in vacuum but light does? »
The basic difference between a sound wave and a light wave is that the former is a ...
Why is it possible to hear noises from far away clearly on cool damp evenings? Is it because sound travels better in cool, damp air than in dry air?»
The most likely explanation for this phenomenon is that warm, damp air at ground level ...
Why do we not hear sound while sleeping or meditating?»
Sleep does not reflect an inactive brain and so we do hear sound while sleeping.  It ...
Why does the flow of ink increases when pens are about to run out of ink? »
When the pen is full of ink, there is very little space for air inside the pen. So while ...
What does Dolby printed on sound systems signify?»
Dolby mentioned in tape recorders and other sound system actually refers to a noise ...
How does audible sound pass through hard material such as a wall and be audible on the other side?»
Sound is nothing but a form of energy. It travels in the form of waves. When these waves ...
Is there any significance in using gravel on railway tracks?»
            Yes, Gravel used on railway tracks is known ...
Why do radios receive signals well only when kept in certain directions?»
  In radio sets, the problem of not receiving signals in certain directions is ...
What are red eye reduction and its function?»
         Many compact cameras and some SLR cameras have ...
Why is it difficult to photograph a TV picture?»
            Engineers have exploited the human eye’s ...
How does a photocopier work?»
                  ...
How does the speed (of vehicles) measuring device used by the traffic police work?»
  Chronometers are used to determine the speed of the vehicle with a hand held ...
Why is it difficult to balance a stationary two wheeler?»
            Stationary objects experience only the ...
Why do metallic vessels lose their initial shine after use? »
New vessels are rubbed on the surface with an abrasive powder. This makes the surface almost ...
Can a fridge, left open in a closed room, be used to cool the room? »
No. Instead it will heat the room. Under normal circumstances, the heat from inside the ...
Why do street lights and head lights of vehicles look like stars when viewed through glass?»
   The star-like appearance can be noticed only when a considerable amount of ...
What is the role of chokes and starter in tube lights? Why do they make noise?»
            Tube lights are discharge lamps. To ...
How is white light split into seven colours when passed through a prism?»
     While the speed of light in vacuum is the same for all wavelengths, the ...
Why do we have sodium vapour lamp in the streets and not mercury vapour lamp?»
            White light consists of seven colours – ...
Can we reduce power consumption by running fans at slow speeds?»
Yes, we can save power with the electronic regulators but not with the old regulators based on ...
When viewed under a tube light, why does a table fan appear to rotate backwards and forwards?»
 Only when lit by electrical lamps, table fans seem to rotate forwards and backwards. ...
Why are fan wings slightly curved?»
Fan wings, also called blades, are curved for optimum air circulation which is determined ...
Why does a bird not get electrocuted on sitting on a live wire?»
   A bird sitting on a live wire will get electrocuted only if electric current ...
How does an electric line testor glow?»
                Electric line testor is used ...
Why is the shadow bigger than the object?»
The shadow is bigger than the object only when the object (o) is nearer to the source of ...
Tube lights do not give sharp shadows like filament bulbs. Why? »
            This can be explained using a simple ...
Why is it marked 6500 K on fluorescent lamps (tube light)? »
The value 6500 K marked on fluorescent lamps represents a parameter called correlated ...
Why does the surface of the incandescent light bulbs become progressively greyer over time? »
The graying of the inner surfaces of incandescent bulbs is the result of gradual ...
Is it true gas filled lamps offer more light compared to ordinary filament bulb for the same power input? If yes how is it possible?»
It is true that gas filled bulbs (mercury or sodium) or tube lights emit more light ...
Why do high tension wires produce a humming sound?»
Air surrounding the conductors of a high voltage overhead transmission line is normally an ...
Why is it that neutron have no charge?»
   The atomic mass is concentrated in the nucleus, the electrons going round it ...
What is static electricity? Why and how is it created?»
Static electricity is electricity that doesn’t move. It is an electric charger held on an ...
Why do electrical appliances draw more current during low voltage? »
Not all electrical appliances draw more current in direct proportion with the reduction in ...
What is Richter scale? How is it used to measure the severity of earthquakes?»
Two basically different methods are used for describing the severity of an earthquake. ...
Why does milk boil and expand so rapidly at a low temperature though some quantity of water is present in it?»
Water boils at 100 degree Celsius and 1 atm. pressure (i.e., pressure at sea level). ...
How do microwave ovens cook food?»
A micro wave oven cooks not with the heat but with the radiation similar to radar waves. ...
How does a pressure cooker work? »
The principle of a pressure cooker is cooking under increased pressure. It is well known ...
Automatic wrist watches stop functioning if not worn even for a day. How does wearing them on our hand make them function?»
    Automatic wrist watches, like any other watch, also need energy for ...
Why does not the cycle travel backwards when we pedal it in the reverse direction? »
It is the free wheel which prevents a bicycle from moving backwards when we pedal in the ...
Why does it seem difficult to cycle up a steep hill than to push the bike up at the same speed? »
A bicycle is unusual among machines because it has a mechanical advantage (MA) of less ...
Why don’t water and oil mix? »
    A phenomenon called polarity prevents oil and water from mixing. All molecules ...
Why is salt soluble in water but not in oil? »
     The solubility of a substance depends on the nature of bonding in both the ...
Why is difficult to tie a knot in a silk lace? »
            A knot in a lace is held together by the ...
Why do bubbles show rainbow colours? »
   Bubbles are balls of thin soap films. They show rainbow colours because the ...
Why do people step down ladders facing backwards? »
  Unlike the steps in a staircase, a ladder has open rungs and is usually set at a ...
Why does writing look reverse in the mirror? »
    Image is produced in a plane mirror by reflection. It is a virtual image, that ...
Why do things burn? »
   Burning is a chemical process in which the material which burns combines with ...
Why do coloured soaps produce white bubbles? »
Foam or lather is nothing but a large collection of small soap bubbles. A soap bubble is, in ...
Why a thin cane does hurt more?»
 As our body is not a flat surface, whenever any part of the body is hit by a stick or ...
Why don’t we need to use spectacles while using a microscope? »
  Spectacles are made up of lenses and are used to improve vision. For nearsightedness, ...
Why do musical instruments sound different? »
  The pitch, loudness, duration and timbre are the four qualities which define the ...
Why is a long stick easier to break? »
     When we try to break a stick by bending it we use lever of the first kind ...
Why is rubber elastic?»
    Natural rubber is made up of long chains of the molecule isoprene with a few ...
Why is there a disturbance on TV when we operate an electrical switch? »
When an electrical switch is operated it produces a spark at the contact point. This spark ...
Why does ice melt when subjected to pressure?»
  One of the laws of fusion is that the melting point of substances which expand on ...
Why do fluorescent tubes consume less power? »
 In filament lamps a good part of the electrical energy is used up in heating the ...
Why does the surface of boiling milk rise? »
            Milk is a fine suspension of fat and protein ...
Why can’t we write with a ballpoint pen on a smooth surface? »
  Ballpoint pens have a tiny ball made of brass, steel or tungsten carbide as their ...
Why is it difficult to run petrol engines with diesel? »
     A petrol engine can’t be run with diesel or a diesel engine run with ...
Why do empty vessels make sounder? »
When an empty metal vessel is struck, the entire surface of the vessel is set into vibration. ...
Why do we need to earth electrical appliances? »
   The earthing of electrical appliances is done as a safety measure. Most of the ...
Why is it easier to balance a long pole vertically on the palm? »
     It is easier to balance a long pole on the palm than a short stick because ...
Why do we need to wear goggles in snow? »
            We need to wear dark sunglasses in ...
Why is it easier to fly a kite with a tail? »
A kite flies better without wobbling, spinning or diving if it can keep itself inclined at a ...
Why does the second hand of a quartz clock move in jerks? »
            The seconds hand of both quartz and spring ...
Why doesn’t soap form lather in hard water? »
   Soaps are salts of fatty acids. Common soaps are water soluble sodium and ...
Why do synthetic fabrics dry so quickly?»
 Synthetic fibres are made artificially. They are solid, smooth and straight in structure ...
Why do boiled eggs become hard? »
            About three-fourths of a poultry egg is plain ...
Why does fanning produce a sense of coolness? »
            Fanning produces a sense of coolness in the ...
Why should we not watch T.V. in a darkened room? »
   The intensity of light coming out from a TV screen is very high. If this bright ...
Why is ice cream softer than ice? »
            The softness of ice cream arises out of the ...
Why does food feel tasteless when we have a cold? »
            There is a close link between the sense of ...
Why do cut onions bring tears? »
            Tears produced by the tear glands keep the ...
Why is it easier to peel boiled potatoes? »
Potato is a living plant tuber (a modified stem specialized for storage of food). There is ...
Why do the leaves of ‘Touch-me-not’ plant fold when touched? »
            All plants respond to touch, but Mimosa ...
Why is lightning accompanied by thunder?»
            Lightning occurs when a massive electrical ...
Why don’t oceans overflow? »
    The reason lies in the water cycle. The total quantity of water in the lakes, ...
Why do the seasons change? »
            The Earth’s axis – the imaginary line around ...
Why do leaves fall? »
The main reason why some trees shed leaves is to conserve water during the winter months. When ...
Why is sea water salty? »
            Sea water is salty because it contains many ...
Why does the Moon’s shadow move west to east during a total solar eclipse? »
            During a total solar eclipse the Moon moves ...
Why are planets sphere shaped? »
  All the planets of our solar system were formed out of the same cloud of gas and dust ...
Why does the Moon show phases? »
 The phase of the Moon as seen from the Earth arises because of the constantly changing ...
Why do stars twinkle? »
            Stars are giant glowing balls of fire ...
Why do earthquakes occur?»
            According to the plate tectonics theory, the ...
Why is the sky blue?»
  The sky as seen from the Earth appears blue because of the scattering of sunlight by ...
Why there are no tides in lakes? »
  The tides are caused by the gravitational pull of the Moon on Earth’s oceans. In fact, ...
Why does fog occur? »
            Fog is a collection of tiny water ...
Why does climate vary from place to place? »
            Climate is the average weather condition of ...
Why are waves higher near beaches? »
            The waves are higher near beaches than in ...
Why do rivers meander? »
            Rivers usually meander when they flow over ...
Why do clouds float? »
            Clouds are large masses of fine water ...
Why is skating possible on ice? »
            Ice skating is an act of gliding over the ...
Why is there a scent after it rains on parched soil? »
            The peculiar smell is produced by the soil ...
Why do the dry beds of ponds and lakes crack? »
            The bottom of lakes and ponds, which usually ...
Why are birds perching on electric lines not killed?»
For any living being to get electrocuted, a current of sufficient voltage has to pass through ...
Why are satellites always launched from the east coast?»
Earth rotates from west to east causing the Sun, the Moon, stars andother planets rise from ...
How does a cell phone work?»
In normal telephone exchange systems, a pair of wires extends each telephone instrument to ...
How are minute quantities (like milligrams, micrograms, or nanograms) weighed?»
Down to milligrams one can use well-designed physical balances-indeed one can even o below one ...
The moon goes around the earth once in 27.3 days, while a lunar month is 29.5 days. Why the difference?»
It is true that the moon makes one rotation around the earth in 27.3 days. A lunar month is the ...
Why is that, whatever they contain, dustbins always smell the same?»
The source of the smell is most probably caused by bacteria and fungi feeding on organic matter ...
What is the difference between radial and ordinary tyres?»
Answer 1. Ordinary tyres or cross-ply tyres are the oldest type of tyre and has a case made ...
Why are a circle divided into 360 degrees?»
The Babylonians 3000 years ago used the hexadecimal system of numbering, which was based upon a ...
Where does sand come from? Has any thought been given to manufacturing it?»
Particles of sand, sometimes sorted by water transport into deposits of remarkably uniform size, ...
What are Euro norms?»
The Euro norms are meant for regulating vehicular emission in Europe. The norms are expressed in ...
How do CFCs damage the ozone layer?»
Most of us don’t think about how our everyday activities might influence the global ...
What are cosmic rays?»
ANSWER 1 Cosmic rays are electromagnetic waves of extremely short wavelength. As the word ...
What is solar wind?»
ANSWER 1 Solar wind is a combination of electrically charged stream of atomic particles – ...
Where does dust come from and why does it reappear so soon after we dust?»
Terrestrial dust is mostly tiny fragments abraded from things; some of it may be even smaller ...

Chemistry

How do we describe the elements livermorium, tennessine and oganesson? »
                        ...
What qualities make nihonium, flerovium and moscovium special? »
                    Nihonium is ...
What are the element numbers 110, 111 and 112? »
                      ...
What are the features of bohrium, hassium and meitnerium? »
                      ...
What are the characteristics of the elements 104, 105 and 106? »
                      ...
What makes mendelevium, nobelium and lawrencium special?»
                    ...
How did the elements 98, 99 and 100 have such curious names?»
                    ...
How did americium, curium and berkelium get their names?»
                      ...
What are the characteristics of uranium, neptunium and plutonium?»
                      ...
What are the element numbers 89, 90 and 91? »
                    ...
What characteristics make radon, francium, and radium unique?»
                   Can an element ...
Who discovered polonium and astatine?»
                      ...
How are the elements thallium, lead and bismuth different from each other?»
                      ...
What is mysterious about mercury? »
               Mercury has always been surrounded by ...
What makes gold people’s favourite metal? »
               Gold is an indispensable metal in our ...
Why is platinum costly?»
               People love to wear on their body ...
Is the nib of a Parker pen made of iridium? »
               Do you use a Parker fountain pen? A ...
What are the characteristics of rhenium and osmium? »
               Rhenium is a tough metal. It is ...
What makes tungsten one of the most useful elements? »
               Thomas Alva Edison is probably a ...
What makes tantalum special? »
               Do you know how the element tantalum ...
Is hafnium used in submarines? »
Hafnium is a silvery grey shiny metal. The element is named after Hafnia, the Latin name ...
What is common between lutetium and Paris? »
               There is an interesting story behind ...
What are the characteristics of ytterbium? »
               Ytterbium is a bright metal with ...
Is thulium used in Euro banknotes? »
               Yes, thulium is used in Euro ...
Why erbium is named so? »
               As we have already seen, many ...
Does the element holmium and the city Stockholm have anything in common?»
               Stockholm is the capital city of ...
What are the characteristics of terbium and dysprosium?»
               Terbium is a silvery-white element, ...
How did europium and gadolinium get their names? »
               You do not have to think too much to ...
How did samarium get its name? »
               Vassili Samarsky-Bykhovets, a Russian ...
What is the connection between promethium and Prometheus, the Greek hero?»
            Prometheus is a ...
Why are praseodymium and neodymium unique? »
                Like twins, these two elements were ...
Who discovered the element cerium?»
               There are three scientists who are ...
Can lanthanum be pulled into a string?»
               Lanthanum is a soft and ductile metal. ...
What are the characteristics of barium?»
               Barium is a soft silvery-white metal. ...
What keeps atomic clocks so accurate? »
               An atomic clock is supposed to be one of ...
What are the specialities of xenon? »
               Xenon is a trace element in the earth’s ...
Does iodine play a significant role in the human body? »
               Iodine is a critical nutrient in ...
Who discovered tellurium?»
               Franz Joseph Muller von Reichenstein, an ...
Was antimony known to man in the Middle Ages?»
               The ancient world was familiar with ...
Is tin one of the oldest metals known to man?»
               Tin is perhaps one of the oldest ...
How did indium get its name? »
            The name of the element indium comes from the ...
What are the characteristics of cadmium?»
               Cadmium is a soft metal, bluish ...
What makes silver special? »
               Silver, like gold, is a popular metal ...
How does white gold get its white colour? »
               Have you seen any ornament made of white ...
Is there an element more valuable than gold?»
              When asked to name some expensive elements ...
Do ruthenium and Russia have anything in common?»
               The first impure form of ruthenium ...
Which is the first element produced artificially? »
               Dmitri Mendeleev had predicted in 1871 ...
What are the characteristics of molybdenum? »
               Molybdenum disulphide, also known as ...
How was niobium discovered? »
               Niobium has an interesting account ...
What makes the elements Yttrium and Zirconium special? »
               In 1789, a Swedish chemist called ...
How did strontium get its name? »
               Strontian is the name of a village ...
What are the features of the element rubidium? »
            Rubidium is a metal which is the 23rd most abundant ...
Is krypton the planet of Superman?»
               Anyone who reads comics must have heard ...
Which is the element that burns your skin? »
                    Bromine is a slightly ...
Is selenium essential for humans? »
               It is unlikely that you have heard ...
Why is arsenic a notorious element? »
                Do you know that arsenic is called the ...
How does germanium get its name?»
               Based on his periodic table, Dmitri ...
Why is gallium an important metal? »
           Gallium is an interesting metal because it is hard and ...
Which element when alloyed with copper is called brass? »
            Zinc, like copper, is a metal which was in use from ...
How did the element of copper get its name?»
            In ancient times, the metal copper was found in ...
Which is the fifth most abundant element on Earth?»
               Nickel is a metal which has been in use ...
Is cobalt magnetic? »
                A magnet attracts or repels other ...
Are we living on an enormous lump of iron?»
              Yes, we are living on a huge mass of iron, the ...
Why is manganese a unique element?»
            The name of the element manganese comes from the ...
Is chromium a new element or was it known to the ancient world?»
               Have you heard of the terracotta army of ...
What is the element that adds strength to steel? »
               You may know that steel, an alloy of ...
Which element did nations accumulate during the Cold War?»
             The Cold War period was a time when nations ...
How did scandium get its name? »
             Sometimes naming an element is difficult and ...
Is calcium the most important element in our body? »
             Imagine humans and animals without bones and ...
What happens when potassium comes in contact with water? »
                    Water is usually used to ...
What keeps some incandescent lamps from burning out? »
             Incandescent lamps were quite common before the ...
Why chlorine is added in drinking water? »
            You may have heard people living in cities complain ...
Why does the titan arum give off a putrid smell? »
              The titan arum is one of the largest flowers ...
Which is the element that glows in the dark?»
            People walking by graveyards ...
Are silicon compounds easily available in our surroundings? »
              You may have made sand castles on the seashore ...
Is the precious stone sapphire just aluminium? »
          No. Sapphire is not made up of only aluminium. However, ...
Is magnesium found in cabbage? »
               Magnesium is an important nutrient for ...
Which sodium compound is an indispensable part of our daily food? »
              Many sodium compounds are common household ...
Which element makes your decorative bulbs glow red?»
            You must have seen the name boards and advertising ...
What helps to prevent cavities in your teeth?»
            Do you know what makes toothpaste manufacturers ...
Which is the element that sustains life on earth? »
               When it comes to maintaining life on ...
How abundant is nitrogen in the universe? »
               A common element in the universe, ...
Is diamond a carbon?»
Diamond is in fact, a type of carbon. Carbon is capable of forming many allotropes. ...
Is boron an element that we come in contact with everyday? »
               Boron is one element that is found in ...
Is beryllium salts sweet in taste? »
Beryllium salts are sweet in taste. But they are very toxic too. The element beryllium ...
What makes your wristwatch tick? »
               You may have seen little thumbnail sized ...
Which element floats a party balloon? »
                ...
Can hydrogen propel rockets? »
               You must have seen the launching of ...
Is the periodic table designed by Dmitri Mendeleev? »
               The periodic table as we know it today ...
What are atoms, if everything is composed of elements? »
               Philosophers in ancient times ...
Is the human body composed of elements? »
               Every part of the human body is made ...
How do we obtain oil? »
                Oil is thought to have formed from ...
How is coal formed? »
               Coal is formed from the compressed ...
How is gold mined? »
               Gold is unusual because it is found ...
How is mining carried out? »
               The earliest form of mining involved ...
What do we obtain by mining? »
                 Mining has taken ...
What are explosives? »
               Explosives are substances that ...
What type of materials are plastics?»
               Plastics are synthetic materials ...
Where does rubber come from? »
               Natural rubber comes from a kind of ...
How is steel made?»
            Steel is made from iron, ...
What are isotopes?»
            The nucleus of an ...
What does half-life mean?»
            Particles continuously ...
What is nuclear fusion?»
            Nuclear fusion is a ...
What is a nuclear reactor?»
            A nuclear reactor is ...
How do nuclear weapons work?»
          Atom bombs are a form of uncontrolled nuclear fission. ...
How do nuclear power stations work?»
                 Once nuclear fission ...
How is nuclear energy produced?»
               Nuclear energy is produced by ...
Natural Properties»
  What are acids?               ...
Natural Properties»
  Why does my breath ‘steam’ in cold weather?       ...
Natural Properties»
What happens when a liquid boils?               ...
What are plastics? »
                 Plastics are ...
Can metals float in water? »
                   Some very ...
What is burning? »
                 When a substance burns, ...
What happens when a chemical substance dissolves? »
                 When sugar is stirred ...
How are crystals formed? »
            Crystals are solid substances that have their ...
What is glass? »
            Glass forms when melted solid materials are ...
What are metals? »
            Almost 80 percent of all elements are metals. ...
Quicksilver »
               Mercury is the only metal that ...
Quicksilver »
               Mercury is the only metal that ...
What are gases? »
               Matter exists in three states: ...
How does radiation change substances? »
                 Radioactivity can ...
What are organic compounds? »
               Organic compounds always contain the ...
How is it possible to make new elements? »
                   New ...
What is radioactivity? »
               Radioactivity is a form of energy ...
Which are the lightest and heaviest elements? »
Hydrogen is the lightest and simplest element, and its atomic number is 1. Uranium is the ...
What is the periodic table? »
             The periodic table is a list of all the ...
What is antimatter? »
                 Antimatter is like ...
Who discovered the structure of the atom? »
                      ...
What are molecules? »
                 The smallest part of a ...
What is ‘Quantum mechanics’? »
               Quantum mechanics helps us to ...
How much space is in an atom? »
               Atoms consist almost entirely of ...
What is at the centre of an atom? »
                 The centre of an atom is ...
Is an atom the smallest type of particle? »
                 There are many smaller ...
Can we see atoms? »
                 Atoms are the smallest ...
How are rocks formed?»
          Sedimentary rocks are formed from the sediment, or ...
Why do river deltas form? »
               A river winding its way down to the ...
Why does smoke go up the chimney?»
               Smoke will rise up the chimney ...
What is fire?»
           Fire is the outward sign that oxygen is combining ...
What is dry ice?»
               Dry ice is frozen carbon dioxide. ...
How is Ink made? »
               Ink is made from a pigment, or dye, ...
Why does iron go red when heated?»
Iron goes red when heated because its atoms radiate vibratory waves of an electromagnetic ...
What is an aerosol?»
An aerosol consists of fine particles of liquid or solid substances suspended in the air, ...
When does copper turn green?»
Although copper is highly resistant to the chemical action of the atmosphere and of sea ...
What is a glass made from?»
Glass is made naturally from a fusion of silica (sand), soda and lime. This fusion can be ...
Why does stainless steel resist rust?»
Stainless steel resists rust because it contains a high proportion of chromium to carbon. ...
Why does an automobile have a carburetor?»
An automobile is driven by an internal combustion engine which will work properly only if ...
What is plastic?»
A plastic, in the modern sense of the word, is a synthetic or man-made material which can ...
When does litmus paper turn Red?»
Litmus paper turns red when placed in an acid solution, but blue is the solution is ...
What is a detergent?»
A detergent is substances which has a power to cleanse. This description applies to soap, ...
Where does the wax go when a candle burns?»
Nowhere- it simply changes into other substances. That is what burning does to everything. ...
Why do some liquids burn?»
Some liquids will burn because when their molecules mix with the oxygen in the air the ...
Why is pollution a problem?»
Pollution is a problem because man, in an increasingly populated and industrialized world, ...
How do fire extinguishers work?»
Fire extinguishers stop flames either by dousing them in water or by dousing them in water ...
What is hard water?»
Hard water is water that contains certain dissolved chemicals that act on soap to form a ...
When does an atom split?»
An atom splits when it is struck by a neutron. The nucleus of the atom then breaks into two ...
Why are some metals chromium plated?»
Some metals are chromium-plated to make them look more attractive and to make them look ...
Why do exhaust fumes contain lead?»
He lead in exhaust fumes comes from the petrol used to drive the internal-combustion ...
When does coal become a precious stone?»
Coal is basically a compound consisting largely of carbon. When a piece of carbon deep ...
What is flint?»
       Flint is one of the various forms of silica, which is ...
Volcanoes»
Why do geysers spout hot water? When water seeps through the ground and reaches ...
Volcanoes»
Volcanic bombs A major volcanic eruption can hurl boulders high into the air. These ...
Volcanoes»
What is lava? Lava is molten rock that reaches the Earth’s surface. Its temperature ...
Volcanoes»
What is a volcano? Volcanoes are openings in the Earth’s crust through which molten ...
Our Planet Earth»
  What are metals? Metals are one of the major groups of elements. ...
RICHES OF THE EARTH»
All the metals we use are taken from the Earth. Most of them are found in rocks, combined with ...
What is glass?»
      What have a window, a light bulb and a ...
What is glass made of?»
    Most of the glass that we use is made in a factory. It is made ...
Making glass»
  Each type of glass is made in a different way. A piece of very thin glass ...
Clear or cloudy glass?»
        Glass is useful because it keeps the ...
Helpful glass»
  Imagine your house without glass – it would be very dark with no windows or ...
Strong glass»
    If you knock a light bulb it will shatter into tiny pieces. ...
Glass and heat»
          Glass can keep heat inside ...
Glass for seeing»
    Do you wear glasses, or have you ever used a magnifying glass ...
Special glass»
  Have you ever wondered how your computer works? The answer is with the help ...
Beautiful glass»
    Glass is not only useful. Glass can be made into works of art. ...
Recycled glass»
      Your glass milk bottle may be made from old glass! ...
A glassy future»
  Today, some glass is mixed with other materials to make it lighter and ...
How oil is formed?»
Oil is a fossil fuel. It is made from the remains of tiny plants and animals called plankton. ...
Black gold»
    Every day millions of people use oil in some way. Yet, it is ...
Finding oil»
    Oil is very valuable. Geologists, people who study rocks, look ...
Oil Drilling deep»
    Drilling rigs are used to drill into the ground to reach oil. ...
From oil-field to refinery»
      Oil is often found in remote places. It is drilled ...
Uses for oil»
  Around 85 percent of refined oil is made into different types of fuel. This ...
Oil and the environment»
    Oil gives us energy and many other things but it also causes ...
Cleaner oil»
  Oil is being made cleaner to help protect the environment. Harmful ...
Oil Running out»
Oil took millions of years to form. Once it is used, it cannot be replaced. We are using it up ...
Saving oil»
    We can all help to save oil. If we use less oil, the oil we do ...
Oil for the future»
    Scientists are working on new ways to power the world in the ...
What is oil?»
    Oil is one of the world’s most important resources. We use oil ...
The future of natural gas»
Although new areas of gas are being found from time to time, we are using up our known supplies ...
Saving gas today»
We can’t replace natural gas but we can use less energy. Insulation and double glazing in your ...
Gas alternatives»
  Natural gas from the ground is not the only gas that we can use for fuel. ...
Will natural gas last forever?»
  We are using up natural gas supplies very quickly. One day, we will run out ...
Natural gas and safety»
    Natural gas burns easily, which makes it useful for providing ...
Natural gas and pollution»
  Each day, we use fossil fuels to drive our cars and to make electricity for ...
Unusual uses of natural gas»
    We use natural gas to heat our homes and to make electricity in ...
Using natural gas»
  Natural gas gives off lots of energy when it burns. Energy makes things ...
Transporting natural gas»
Gas can be taken from the ground and sent through a network of pipes to homes around the world. ...
Drilling for gas»
      Have you ever dug a hole in some sand or in the ...
Where do we find natural gas?»
    Natural gas forms deep under the ground or under the seabed. It ...
What is natural gas?»
Natural gas is invisible. It has no colour, shape or smell. But when gas burns, a flame ...
Important iron»
    The centre of the Earth is partly made of iron! Around the ...
Light and strong Metals»
    Many metals, such as iron and steel, are strong and heavy. They ...
Useful metals»
    You can see and touch metals used in things like drink cans and ...
Metals - Shiny and gold!»
  Gold, silver and platinum are special metals. They are used to make ...
Metals - Old to new»
Much of the metal we use has been used before. You can use metals again and again, by melting ...
Metals in the future»
We use metals every day. Our lives would be very different without metals. Scientists are ...
Metal Bend and stretch»
    Metals are strong, but they can be made into many shapes. There ...
Mixing metals»
    Some metals can be used on their own. Copper is used to make ...
Rock of metal»
      Before we can use metal and make it into useful ...
Mining for metals»
  You can find some metals in rivers or buried at the bottom of the sea. ...
Where metal comes from?»
    Most metals are found inside rocks, at the bottom of the sea ...
What are metals?»
  Metals are everywhere! You can see and touch metals in the kitchen, in the ...
The advantages of nuclear power»
  Nuclear power is made without burning fuels that release harmful gases. ...
The disadvantages of nuclear power»
    Many people worry about the safety of nuclear energy and the ...
Nuclear accidents»
    Nuclear accidents have been caused by leaking pipes and ...
Nuclear power and safety»
        There are many safeguards to make sure ...
Nuclear waste»
    No one knows what to do with waste from a nuclear reactor. ...
Nuclear energy today»
      Accidents have made nuclear power unpopular. But we ...
Future developments of Nuclear Power»
    Nuclear power may become more popular in the future. Oil and gas ...
Nuclear weapons»
    The most terrible and destructive weapons are made from nuclear ...
Other uses of nuclear energy»
  Nuclear energy has many other uses. Small amounts of radioactive materials ...
What are the uses of Nuclear energy?»
      Today, nuclear power is mainly used to make ...
What about uranium?»
    All about uranium The fuel used to produce nuclear power ...
What is nuclear power?»
    Nuclear power is a type of energy. Some countries use it to ...
Wood for the future»
  Wood is a valuable material that is used every day all over the world. ...
Wood for life»
    Trees are very important for all the life on Earth. They help ...
Wood for animals»
      Many animals use wood. Some use it as a building ...
Paper – making »
      Most of the conifer trees grown in plantations ...
Wood for medicine and food»
    Many of the foods and medicines we use come from rainforest trees ...
Wood for fuel »
    Many people all over the world use wood for burning. Wood is a ...
Wood Work»
      Wood is a very useful material and is used to make ...
Trees cutting and moving»
    After the trees are cut down they are taken away. Most logs are ...
From seed to timber»
    Most of the wood we use is specially grown in large forests. These ...
Wood close up»
      Each year a tree grows a new layer of wood. The rings ...
Wood from trees»
  The wood we use comes from two types of trees. One type is called ...
What is wood?»
      Wood is an amazing natural material. It is used ...
Plastic for the future»
  The oil we use to make plastic is running out. Oil takes millions of years ...
Recycling plastic»
      Plastic can be recycled and made into something new. ...
The problem with plastic»
      Plastic is a very useful material but it also causes ...
Plastics for health »
  Plastic can be used to keep us healthy. Hospitals use plastic because it is ...
Plastic clothes»
    Some of our clothes are made from plastic. Fabrics made from ...
Which things wrapped in plastic?»
  All wrapped ...
Bubbly Plastic»
  Plastic can be made into foam. Foam is made by blowing bubbles of gas into ...
Making things with plastic»
    There are different ways of making plastic into the shapes we need. ...
What are the different types of plastics?»
        There are hundreds of different kinds ...
How is plastic made?»
          Oil is drilled and pumped out ...
What is the history of plastic?»
               Around 150 years ago, people did not ...
What is Plastic?»
                      ...
What are Antifreeze Compounds? »
               Antifreeze compounds are those ...
What are fuel gases? »
               The use of gas for cooking and ...
What is Carbon Cycle? »
               Of all the elements known to man, ...
What is Ceramics? »
               The word ‘ceramics’ has its origin ...
What is the absolute zero? »
               It is our common practice to measure ...
How do ice columns grow inside caves? »
               Ice columns appear in many caves or ...
How do we get common salt? »
               It has been estimated through ...
Can fresh water be obtained from the Sea? »
               We all know that sea water is salty. ...
What is Osmosis? »
               It is a well known fact that when ...
How is wax made? »
            Wax is an insoluble solid fatty substance that is ...
What is ammonia gas? »
                Ammonia gas is a colourless ...
What is Quantum Theory? »
               We know that light is a form of ...
How does a wet Battery work? »
               A battery is a device that produces ...
How is sugar made? »
               Sugar making process was known in ...
Why does camphor change into gas without turning into a liquid first? »
               Usually when solids are heated they ...
How does a motorcycle engine work? »
              We all know that a motorcycle is a ...
How does a hair drier work? »
               Sometimes, when we visit to a ...
What is Greenhouse Effect? »
               We all know that rapid ...
What is a Chemical Warfare? »
          A chemical warfare involves the use of chemical ...
What are solar flares? »
          A solar flare is defined as a sudden intense brightening ...
What is a poison? »
            A poison is a toxic substance that is damaging to ...
What are the methods of sewage disposal? »
          Sewage is a watery mixture of all wastes that come from ...
How is cheese made? »
          Today, there are a variety of cheese made from the milk ...
What is ozone gas? »
          Ozone is a form of oxygen in which each molecule ...
What are pesticides? »
            Any plant or animal that occurs in such abundance ...
What is Carbon Dating? »
          Man’s curiosity has always led to the opening of new vistas ...
How are different paints made? »
          Paint is a mixture of one or more coloured powders and a ...
How do detergents perform the cleaning action? »
The word ‘detergent’ means any substance that cleans things. But today the word is usually ...
What is a welding torch? »
               A welding torch is a mechanical device ...
How do we measure the hardness of materials? »
            Hardness is a characteristic property of the ...
What are the different abrasives? »
          An abrasive is a substance used for grinding, cutting, ...
What is electroplating? »
               Electroplating is a process of metal ...
How is sulphuric acid manufactured? »
          Sulphuric acid is called the king of acids because of ...
How do deep-sea divers operate? »
           Since ancient times, man’s curiosity has led him to ...
When was the Sahara desert covered by Ice? »
          Sahara is the world’s largest desert covering an area of 9 ...
What is the Nitrogen Cycle? »
          Our atmosphere contains about 78% of nitrogen. A certain ...
What are proteins? »
          Proteins are very important chemical compounds contained ...
What is a litmus paper? »
          Litmus is used in chemistry to detect the presence of ...
When were anaesthetics first used in operations? »
          Before the discovery of anaesthetics, an operation used to ...
What are enzymes? »
            The human body is a machine that needs energy to ...
What is blood pressure? »
          The heart is a vital organ that pumps blood to different ...
What is the Iron-lung machine? »
          The iron-lung machine was one of the earliest ...
What causes asthma? »
          Asthma is a chronic disease of the lungs in which a person ...
What are the functions of arteries and veins in our body? »
Blood must reach every cell in the body to provide it with food and oxygen, and to remove waste ...
What is the function of liver in our body? »
          The liver is a large and vitally important organ in the ...
What is allergy? »
          Hay fever, rashes on the skin, reactions to certain ...
What is blood cancer or leukemia? »
          Leukemia or blood cancer is a fatal disease of the ...
What is albinism? »
          Albinism has been derived from the Latin word ‘albus’ which ...
How do urine tests help in diagnosis of diseases? »
          Diagnosis of different diseases by urine examination has ...
What is the Theory of Relativity? »
In the early nineteenth century people believed that light travelled through imaginary ...
How is nylon made? »
            Nylon is one of the most important chemical ...
How is electricity conducted through wires? »
Electricity is supplied to our homes, schools, factories and stores through copper or ...
How does an automobile engine work? »
          An automobile such as a car is an automatic self-propelled ...
How are hard drinks made? »
          Wine is probably the first type of hard drink to have come ...
How are matches made? »
            When a strip of wood, cardboard or waxed paper ...
What are the different types of thermometers? »
          A thermometer is an instrument used for measuring the ...
Why do some acids cause burn? »
            An acid is a chemical, which when dissolved in ...
How are different dyes made? »
        Dyes are colour substances which impart their colour to the ...
What is dry cleaning? »
Man has been using soap and water as cleaning agents for thousands of years. The first soap ...
What is quartz? »
          Quartz is a hard, glossy mineral made of silicon and ...
What is a Mass Spectrograph? »
               A mass spectrograph is an instrument ...
How can we extinguish fires? »
          We are all aware of the damage and disaster a fire can ...
What is Heavy Water? »
          We know that ordinary water is a compound of hydrogen and ...
What are quarks? »
            All matter is made up of small particles called ...
How does soap clean things? »
           Ordinary water does not remove dirt from things ...
How does a fluorescent light work? »
          Man has been using artificial lights ever since he ...
How is cement made? »
          Cement, today, is by far the most useful of all the ...
How can we test the purity of pure ghee? »
          Pure ghee and vanaspati ghee are a part of our daily ...
What are isotopes? »
All elements are made up of tiny invisible particles called atoms. According to the ...
What are alloys? »
          An alloy is an intimate mixture of two or more substances, ...
What are sulfa drugs? »
          Sulfa drugs are synthetic chemicals that are used to treat ...
What are the different forms of energy? »
          To the economist, energy is a synonym for fuel; to the ...
How is light produced by an electric bulb? »
The moment we switch on an electric bulb in a dark room in the night, the whole room is ...
What is a nuclear reactor? »
               A team of scientists in Chicago, ...
Why does iron get rusty? »
          Rust is a brownish red substance that forms on the surfaces ...
What is the structure of an atom? »
               According to the ancient philosophers, ...
Can matter be converted into energy? »
        In 1905, Albert Einstein, established a relationship between mass ...
What are the wonders of X-Rays? »
          X-rays are invisible electromagnetic radiations. Their ...
How does a thermos flask work? »
           The thermos flask is a special kind of bottle in ...
What are the different states of matter? »
          Anything that occupies space and possesses mass or ...
How is weather forecast made? »
          Weather is the day to day changes in the state of the ...
What is pasteurization? »
          Normally if fresh milk is not boiled for sometime it ...
What are infra-red radiations? »
          We know that the sunlight consists of all those colours ...
How are millions of substances made from only a few elements? »
          The number of naturally occurring stable elements on the ...
Which material does not burn in fire easily? »
          Whenever any substance is put in to fire it burns and ...
How does a pressure cooker work? »
          Pressure cooker is a modern kitchen appliance that can cook ...
Does any metal exist in a liquid state? »
               Mercury is the only metal that exists ...
What is diamond? »
          Diamond is the most precious and enduring substance in the ...
How is iron obtained from the earth? »
          Iron is found everywhere on earth. It is not only ...
Why does bread have pores? »
          Bread is a popular food in almost all the countries of ...
What is fire? »
          A material that burns combines quickly with oxygen in the ...
What is smoke? »
          Whenever wood, coal or some other substance burns, smoke ...
How are icebergs formed? »
          In the Southern Hemisphere, the Antarctic ice sheet ...
Why do we perspire? »
          Our body is like a furnace. The food we eat acts like fuel ...
How is soil formed? »
          Soil is the upper most surface layer of the earth in which ...
What are pain relievers? »
          A pain reliever is a drug that reduces pain without causing ...
How can we test the purity of milk? »
             The instrument used to assess the purity of ...
Who created the Frankenstein’s monster? »
           In the 18th and 19th centuries, science fictions ...
What is a Hydrogen Bomb? »
          Soon after the development of the atom bomb in 1945 ...
How are valleys formed? »
          The wide, broad plains or uneven tracts with gradual ...
What is LPG? »
         The term LPG stands for liquefied petroleum gas. LPG is ...
What is an Alkaline Battery? »
A battery is a device that produces electricity by chemical action. A battery contains one or ...
How is synthetic rubber made? »
                  Rubber, which is in common use, ...
How does a dish washer work? »
A dishwasher is a modern domestic appliance that cleans and dries utensils automatically. These ...
How does a washing machine work? »
          A washing machine is an electrically operated machine used ...
What are the constituents of milk? »
          Milk is white nutritious liquid produced by female mammals ...
What is Water? »
Like air, water is essential for life. Without water we cannot survive for more than a few ...
What is Uranium? »
           Uranium is a silvery, radioactive, metallic element. ...
How is silk produced? »
                   All of us are familiar ...
How do we get petrol? »
Petrol is one of the most useful products in the world. Cars, scooters, aeroplanes and various ...
What is marble? »
Marble is a kind of lime stone which is available in many colours. White marble has been in ...
What are antibiotics? »
                Antibiotics are special kind of ...
How are the Pearls formed? »
  Pure pearls are very precious. You will be surprised to know that only a small ...
What is Plastic Surgery? »
              Plastic surgery is a branch of surgery devoted ...
What is Plastic? »
            Plastics do not occur naturally but are ...
What is dry ice? »
Ice, which we generally see around us, is made by freezing the water. Water turns into ice ...
How do we get Wool from Sheep? »
             Warm clothes that we wear during the winter are ...
How is copper useful to us? »
              Copper is a reddish orange metal that has ...
What is helium? »
Most of the gases can be prepared in the laboratory but there are some which are found in ...
How is oxygen useful to us? »
                 Without oxygen there would have ...
How is liquid converted into vapour? »
                 It is commonly observed during ...
How is Silicon useful to us? »
Silicon is a non-metallic element. It is not found in nature in a pure form. Pure Silicon is ...
Why do hot things burn us? »
             An object is said to be hot if its ...
How is dew formed? »
                 You might have seen small drops ...
Are the molecules of all substances in motion? »
              Every substance is made up of very tiny ...
Why is gold so costly? »
From the very ancient times man has a deep fascination for this shiny yellow coloured metal ...
How is dust useful to us? »
          It is a general belief that dust is very harmful to us. But ...
Why does ice float on water? »
          It is a matter of common experience that ice floats on ...
What is Polaroid photography?»
Polaroid photography is a photographic process in which the processing of the exposed film ...
What is Quartz clock?»
It is a clock which makes use of the piezoelectric properties of quartz. A quartz crystal has ...
What is Relativity?»
The theory of relativity was put forth by Albert Einstein in two parts. The first part called ...
What is SETI?»
SETI is an acronym for Search for Extra Terrestrial Intelligence. The possibility that ...
What is Solar wind?»
The solar wind is a stream of charged particles flowing out from the sun’s outer atmosphere or ...
What is Stainless steel?»
A common term used to cover an entire range of iron-base alloys that are remarkably resistant ...
What are Sunspots?»
A sunspot is a relatively cooler region on the surface of the sun. For an observer on earth, ...
What is Superconductivity?»
Superconductivity is a property which enables electricity to flow through a conductor without ...
What is Teflon?»
Teflon is the trade name of a fluorine containing polymer chemically known as ...
What is Ultrasound?»
Any sound of frequencies above the limit of human hearing, that is, 20,000 hertz or more, is ...
What are Vaccines?»
Vaccines are preventive medicines which when introduced into the body protect it from a ...
What are Plastics?»
The word plastics come from the Greek word Plastikos which means ‘to shape’ or ‘able to be ...
What is Plastic money?»
Plastic money refers to the use of instruments like credit cards instead of cash in business ...
What is Photovoltaics?»
The conversion of electromagnetic radiation like sunlight into electricity through absorption ...
What is Pacemaker?»
The pacemaker is a battery operated electronic device which transmits electrical impulses to ...
What is Ozone hole?»
There is a thin layer of ozone that circles the earth at a height of 15-50 km. Its protective ...
What is Optical fibre?»
It is a thin, cylindrical cable made of glass fibre used for transmitting light signals. Light ...
What is Nuclear waste?»
In nuclear reactors a number of radioactive waste products are produced as the fuel is used ...
What is Nitrogen fixation?»
Nitrogen is essential for plants and animal life as it is a constituent of major bimolecules ...
What is Mutation?»
A change in the structure of a gene resulting in an altered gene product, that is a ...
What is Magnetic storm?»
It is a phenomenon caused by disturbances in the earth’s magnetic field. It gives rise to ...
What is MRI?»
MRI or the Magnetic Resonance Imaging is a technique for obtaining images of organs for ...
What is LPG?»
LPG, an acronym for Liquefied Petroleum Gas, is the most popular cooking fuel used in urban ...
What is Liquid crystal?»
Some kinds of liquid crystals can rotate the plane of polarized light and this property is ...
What is Hydroponics?»
Hydroponics is the commercial method of growing plants without using soil, by seeding them on ...
What is hologram?»
A hologram is a pattern recorded on a photographic plate or film using laser illumination ...
What is Quicksand?»
Quicksand is a bed of loose sand mixed with water. It is found in places such as river banks ...
What is Radio telescope?»
Radio telescope is a device to receive radio-waves from space. Radio-waves are emitted by a ...
What is Remote control?»
Remote control is a technique of operating a system from a distance. The operating system may ...
What is Heatstroke?»
Heatstroke is a condition when the heat regulating mechanism of the body breaks-down. ...
What is Global warming?»
Global warming is the phenomenon of a gradual overall increase in the average temperature of ...
What is Genetic engineering?»
Genetic engineering is a technique of manipulating the DNA in cells to endow an organism with ...
What is Gene therapy?»
Gene therapy is a new and as yet largely experimental branch of medicine that incorporates ...
What are Fullerenes? »
It is a family of newly discovered, the third allotropic form of carbon, quite distinct in ...
What are Composites?»
Composites are materials made by combining two or more substances— one called the ...
What is Cholesterol?»
Cholesterol is a complex fatty substance that is essential for the normal functioning of the ...
What is Catalytic converter? »
Catalytic converter is a device, fitted onto the exhaust pipes of petrol-driven automobiles ...
What is Cancer? »
            Cancer is the ...
What is Biopsy?»
Biopsy is a simplified procedure of obtaining tissues from affected part(s), usually some ...
What is Biodegradation?»
This is the process by which living organisms breakdown matter into its simpler ...
What is Detergents? »
Detergents are synthetic chemical salts which change the surface property of water and which ...
What is Dialysis?»
Dialysis is a process of separating dissolved substances from a solution using a semi-permeable ...
What is Atomic dock? »
Atomic clock is a device for measuring time. It makes precise measurements of time. It makes ...
What is Amniocentesis? »
It is a diagnostic technique to check for genetic abnormalities in unborn babies. The test ...
What is Allergy?»
Allergy is a state of hypersensitivity acquired through the exposure to a particular substance, ...
What is AIDS?»
Acquired Immune Deficiency Syndrome (AIDS) is the most devastating and fatal disease of the ...
What is Acid rain?»
It is a phenomenon caused by industrial pollution. Natural rain always contains a small amount ...
How does Polish shine shoes? »
The shine of a surface depends on its smoothness. Smoother the surface, more it will reflect ...
How is Curd formed? »
Curd is formed by a chemical reaction which involves casein, the protein that occurs in milk. ...
How do Naphthalene balls keep away moths? »
The naphthalene balls used for keeping away harmful insects from damaging clothes are ...
How do Woollens keep us warm? »
Wool fibres are made of a particular protein (Keratin) which is a bad conductor of heat and as ...
How is Hail formed? »
Hail is formed in thunder clouds when ice pellets formed near the freezing level in the ...
How do Plants absorb nutrients from soil? »
Plants have special structures called root hairs for absorbing water and other nutrients from ...
How are Annular rings in plants formed? »
The annular rings or the alternating dark light circles seen in a cross section of a tree ...
How does Water rise in tall trees? »
Cells in the root hairs of plants contain dissolved sugars and salts. Water surrounding the ...
How do Igloos keep occupants warm? »
An igloo is comfortable because ice is a bad conductor of heat. It does not allow the heat ...
How is Expiry date of drugs determined? »
Most medicines, which are chemical compounds and their combinations, degrade with time. This ...
How do Herbicides kill weeds? »
Herbicides are chemicals used to destroy weeds without harming the useful crops. This is ...
How do Seeds sprout? »
Seeds sprout when favourable temperature (15.38°C), enough oxygen and moisture are available. ...
How do Fishes survive in frozen lakes? »
Lakes which appear frozen from the top never freeze completely. Only the top layer freezes and ...
How do Animals see at night? »
No animal can see in total darkness. However, some animals are capable of making use of faint ...
How do Lizards walk on walls? »
The feet of lizards are adapted for walking on rough as well as smooth surfaces. The lizards ...
How do Spiders spin webs? »
Spiders spin webs as a means of trapping insects. They have special organs called ...
How do Bees communicate? »
Besides chemicals called pheromones, bees use a kind of dance language to tell other bees in a ...
How do Bees make honey? »
Honeybees suck nectar from a wide variety of flowers. But each bee usually keeps to a ...
How do Camels survive in deserts? »
Camels can survive for days in deserts with little food and no water due to their unique ...
How do Fish generate electricity? »
Electricity in fish is generated by the normal functions of nerves and muscles together with a ...
How do Bats fly in the dark? »
Bats navigate by making use of sounds that they emit. The way these sounds bounce off from ...
How do Chameleons change colour? »
It is not quite correct to say that a chameleon can change its colour to match coloured ...
How do Dogs track culprits? »
All dogs have keenly developed senses of smell and hearing. Dogs naturally depend on their ...
How do Animals identify their off springs? »
Many methods, not all fail-safe seem to be used by the animals in identifying their young. ...
How is Artificial insemination done? »
Artificial insemination is a method used in animal husbandry to genetically upgrade stock by ...
How does Sunlight produce vitamin D? »
Vitamin D is a group of about 10 fat soluble compounds. The form of vitamin D produced in ...
How is AIDS detected? »
AIDS is caused by a virus called Human Immunodeficiency Virus or HIV. The presence of this ...
How is Blood sugar measured? »
Sugars in our diet are converted into the glucose due to metabolism and which then goes into ...
How does Mehendi colour skin? »
Mehendi or henna leaves contain a colouring matter called lawsone. This is a dye which can bind ...
How does Paan stain mouth? »
Chewing paan without kattha will not stain the mouth. The mouth turns red on chewing paan with ...
How do Balms relieve pain? »
Pain is felt when the message reaches the brain via the nerves and the spinal cord. The ...
How is Water purified? »
Water supplied to cities and towns is usually taken from rivers or lakes and contain various ...
How do Fireworks display colours? »
The brilliant white, sparkling yellow, glowing red and the shimmering blue colours in the ...
How does Shampoo Produce lather? »
Lather or foam is nothing but a collection of tiny soap bubbles. There is always a large ...
How do Metals corrode? »
The corrosion of metals is caused by chemical reaction. Water, salts, acids and gases — all ...
Why can’t ornaments be made with pure gold? What is the purity (in percentage) of 22 carat and 18 carat gold?»
Ornaments could be made of pure gold but would get easily pressed out of shape. This is ...
What is Pasteurization? Is it a process of sterilization? »
Pasteurization is defined as the process of heating milk to a particular temperature and ...
Why do plastics become brittle when exposed to the Sun for a long period?»
Plastics are made of polymers which giant molecules are having long chains of repeating ...
How does soap clean our clothes? »
A soap molecule is made up of 2 parts - a long hydrocarbon part and a short ionic part ...
Do normal hand soaps actually kill germs? We are always encouraged to wash our hands after a visit to the toilet, but does this really make much difference? »
Ordinary soap has little value as an antiseptic and it does not kill or inhibit many types ...
Why is zeolite used in the purification of water? »
Zeolite is used in the purification (more correctly softening) of water. Water in some ...
Why does continued use of hard water result in the formation of a layer in utensils, water filters and boilers?»
Water contains dissolved salts of calcium, magnesium and often iron in the form of ...
How does potassium cyanide cause sudden death? »
Potassium cyanide when consumed causes death by gradually arresting the supply of oxygen to ...
What causes cooling when glucose is dissolved in water?»
Formation of a solution is a physico-chemical process. When two substances mix to form a ...
What is fire made of? What is its atomic structure? What causes things to burst into flames in the first place and why can't all materials be made to produce flame? »
Fire involves a chemical reaction between fuel and atmospheric oxygen.  Once initiated ...
Why don’t identical twins have identical fingerprints? »
Fingerprint formation is like the growth of capillaries and blood vessels in angiogenesis. ...
Why is the sting of a scorpion more painful than that of a snake sting? What are the chemicals in their poisons?»
Scorpion’s venom acts on the nerve tips and roots whereas snake’s poison acts on dendrites ...
How do trees reduce air pollution?»
            Plants can prevent pollution of ...
Why do vegetables such as cucumber, snake gourd and bottle gourd sometimes taste bitter? »
   Bitterness is cucumber and other cucurbitaceae vegetable is due to the ...
How can we identify poisonous and non-poisonous mushroom? »
                  ...
What makes a cola foam up when you put a pretzel in it? »
The cola foaming up when a pretzel is put in it is a physical interaction, not a chemical ...
Why does boiled water lose taste? »
            Naturally ...
Does cold water extinguish fire faster than hot water? »
                ...
Why are soap bubbles and oil layers coloured?»
 Coloured bands on soap bubbles and oil layers are caused by interference ...
How does carbon change into diamond?»
 Carbon changes into diamond and graphite in the depths of the earth under high pressure ...
What does 43 and 53 grade cement mean?»
Grade denotes the minimum strength obtainable in a cement sample.  This is determined ...
Why don’t water and oil mix? »
    A phenomenon called polarity prevents oil and water from mixing. All molecules ...
Why is salt soluble in water but not in oil? »
     The solubility of a substance depends on the nature of bonding in both the ...
Why is difficult to tie a knot in a silk lace? »
            A knot in a lace is held together by the ...
Why do bubbles show rainbow colours? »
   Bubbles are balls of thin soap films. They show rainbow colours because the ...
Why do coloured soaps produce white bubbles? »
Foam or lather is nothing but a large collection of small soap bubbles. A soap bubble is, in ...
Why does ice melt when subjected to pressure?»
  One of the laws of fusion is that the melting point of substances which expand on ...
Why does the surface of boiling milk rise? »
            Milk is a fine suspension of fat and protein ...
Why doesn’t soap form lather in hard water? »
   Soaps are salts of fatty acids. Common soaps are water soluble sodium and ...
Why do synthetic fabrics dry so quickly?»
 Synthetic fibres are made artificially. They are solid, smooth and straight in structure ...
Why does food feel tasteless when we have a cold? »
            There is a close link between the sense of ...
Why do cut onions bring tears? »
            Tears produced by the tear glands keep the ...
Why is sea water salty? »
            Sea water is salty because it contains many ...
Why is there a scent after it rains on parched soil? »
            The peculiar smell is produced by the soil ...
Why do the dry beds of ponds and lakes crack? »
            The bottom of lakes and ponds, which usually ...
What are the different types of handshakes?»
            When you meet another ...

Biology

What is migration?»
            Migration is a ...
Can all birds fly?»
            No, not all birds fly. ...
Which birds fly the fastest?»
            The fastest known bird ...
Which is the largest flying bird in the world?»
            The Andean condor, with ...
How do feathers get their colours?»
               Colours in the feather of a bird are ...
What are the functions of feathers? »
            Bird feathers, which evolved from the scales of ...
Are feathers the main characteristics of a bird?»
                      ...
How did birds evolve from reptiles? »
                    It all started some ...
How many kinds of birds are there? »
                    About 9,000 different ...
How are fishes classified? »
               The number of fish species runs to ...
What is the anatomical structure of a fish?»
               If you carefully analyse the fish in ...
How did fishes evolve? »
          Can you imagine rivers, lakes or great oceans without ...
Which is the largest group among vertebrates?»
                  Vertebrates represent the ...
What are fishes?»
               Have you ever gone fishing in a lake ...
Are many species of reptiles in India in grave danger?»
            Snakes in India are ...
What is a tuatara? »
               Our Earth is a sanctuary of ...
Do some snakes fly? »
               Although snakes frighten us in ...
Which island is named after a tortoise? »
               There is a group of is islands 965 ...
Why crocodiles and alligators are considered clever hunters? »
            Some reptiles are excellent hunters. Crocodiles ...
What is Archaeopteryx? »
               We all have seen dragons in movies. ...
Did snakes evolve from lizards?»
                We are all scared of snakes. Have ...
How did the present-day reptiles evolve?»
               Scientists say that in the ancient ...
What is a reptile? »
            Who will not have chills ...
Why are the Western Ghats important for amphibians?»
            Various life forms need ...
Why is the respiratory system of amphibians different?»
            We breathe through our ...
Why is water important for amphibians?»
            Scientists say that life ...
How did amphibians originate?»
            In the course of the ...
How are amphibians classified?»
            There is a huge variety ...
What is an amphibian? »
            If a fish is taken out ...
Why is the giraffe a giant among mammals?»
           We all know that the giraffe is the tallest animal ...
Which animal is known as the ‘river horse’? »
               Some animals love spending time in ...
Why are rhinos in danger of extinction? »
               The rhino is a strange, wild animal ...
Why do zebras have stripes? »
                  The wild is a place of ...
Which is the commonest wild member of the horse family?»
            Among the animals that ...
How are Bactrian camels different from Dromedary camels?»
             There is so much diversity among mammals. ...
Why camels are called ‘ships of the desert’?»
              In the olden days, when science was not as ...
Which animal did Man domesticate for the first time?»
               Man has domesticated so many ...
Are rabbits and hares different from each other?»
            We have heard the story ...
What are flying foxes?»
            Do foxes fly? No foxes ...
How do bats find their pray?»
            Can you walk in the ...
What makes the bat a unique animal? »
...
What are insectivores? »
...
Why are most marsupials found exclusively in Australia? »
...
Why do some mammals have pouches?»
...
Why is a squirrel called a gnawing animal? »
...
Why the aardvark is called an animal jigsaw? »
...
Why are some mammals ‘toothless’? »
...
Why do some mammals lead a wandering life? »
...
Why do mammals have hair or, their body? »
...
Why is it said that mammals have a two-in-one heart?»
...
What is special about the platypus and echidnas?»
               We know that a mammal is an animal ...
Why are the babies of mammals attached more to their mothers than fathers?»
               Have you ever thought of the wonder ...
How did mammals become lords of the earth? »
               Physical prowess and the ...
Is it true that mammals come from reptiles?»
            Sometimes, myths and ...
How are mammals classified? »
          How many kinds of mammals can you think of? Even if we ...
Why mammals are called the most advanced animals? »
               How did Man become the most ...
What makes mammals special animals? »
               What is the difference between a cow ...
What is a mammal? »
               Life on earth is sustained by ...
What are the characteristics of vertebrates?»
            Vertebrates are called ...
Why some animals are called vertebrates? »
               Man’s existence depends on not only ...
How are starfish different from other fishes?»
               Life underwater is so diverse and ...
Why are honeybees so special?»
               One of the ways nature contributes ...
What are the characteristics of insects? »
               Insects are so common that we hardly ...
What is an octopus?»
               The octopus does not have a ...
What are molluscs?»
               It is unlikely that you are familiar ...
What is a jellyfish? »
               Although the jellyfish has ‘fish’ in ...
Why are corals special? »
              Have you seen pictures of colourful coral ...
What is a sea sponge? »
               When we hear the word sponge, what ...
What are some key characteristics of invertebrates? »
               Invertebrates, as the name suggests ...
How are invertebrates classified? »
               There is so much diversity among ...
Does the size of invertebrates mean that they are less important in the ecosystem?»
            Most invertebrates that we are familiar with are ...
Are invertebrates intelligent? »
              Which is more intelligent: a dog or a ...
Are invertebrates generally small? »
               Can you observe some of the animals ...
How do invertebrates protect themselves from danger?»
            Those animals with ...
How do animals survive without a backbone?»
              What, do you think, would happen if we had ...
What are invertebrates?»
              Have you seen the picture of the skeleton ...
Do animal classifications change? »
              Classifying animals into groups was based ...
What is the binomial system of scientific names?»
              Do you know that all the animals that we ...
Who classified animals first? »
                   From the time ...
What is the purpose of classifying animals? »
            When you are going to appear for an important ...
How are animals classified? »
          How many kinds of animals do you know? If you start ...
What is the Theory of Evolution?»
Science was never satisfied with the creation myths of various religions that explained the ...
Why did organisms move from the oceans to land? »
          While the oceans provided the most conducive atmosphere ...
How did Miller’s experiment contribute to the study of evolution? »
            We cannot travel to the past to see how life began on ...
Why is it said that life began in the oceans? »
              Have you tried to stay underwater holding ...
What come first-plant or animal? »
               From time immemorial, the question ...
How do plants and animals differ from each other?»
            You must have observed huge ...
What is an animal? »
            Life is what makes our ...
Why do some people believe that global warming is not a threat?»
                        Is ...
Is it true that by saving water and electricity we are helping our environment?»
            Water is one of the ...
How do we conserve energy? »
                Energy is essential for the ...
Why is avoiding plastic essential?»
                  Plastic has become an ...
Why should we plant trees? »
              Do you know that looking intently at the ...
What was the goal of the March Against Monsanto?»
              Farming and agriculture date back to the ...
What is the significance of ‘Camps for Climate Action’ campaign? »
              Conserving the environment and nature is ...
What is the Xinfa Aluminum Plant protest?»
          Factories and manufacturing plants are major sources of ...
What was the purpose of the ‘Save Manapouri Campaign’?»
Have you been to a dam site? Dams stop a large body of water such as river or lake from ...
Who was Sunderlal Bahuguna? »
            Hugging is not just an act to show that you love ...
How significant is Sunita Narain in the context of conservation of environment in India? »
            Sunita Narain was born in Delhi and she started ...
What makes Mike Pandey a prominent figure among other Indian environmentalists? »
              You can express your love and concern for ...
What is Medha Patkar’s role in environment conservation in India?»
            Nature has a rhythm and ...
What is Vandana Shiva’s contribution to the Indian environmental scenario? »
              Since it is the second most populated ...
Who was David Brower? »
              David Brower was a mountaineer and ...
What are the contributions of the environmentalist Chico Mendes?»
            The earth breathes through forests. If forests ...
Who is Wangari Maathai? »
            Who, after one’s studies, would not like to get a ...
Was Henry David Thoreau an environmentalist?»
            Have you ever felt calmer and more at peace with ...
Who was Aldo Leopold?»
            Is Man the custodian of the earth? For thousands ...
Who is the founder of modern environmental movements?»
          Form the latter part of the 19th century onwards, ...
Who is John Muir, the man of the mountains?»
            Great men are those who ...
What are the goals of GAW?»
            Our planet today is not ...
What is AOSIS?»
            Climate is changing ...
What does the International Renewable Energy Agency do?»
            Nature is a treasure trove ...
What are the goals of the Global Environment Facility?»
                ...
What is IUCN?»
            As the world is getting ...
Why is it important to reduce the use of CFCs?»
            Although ...
How does ozone depletion happen?»
            The ozone layer is a ...
Is there variation in ozone distribution?»
            The ozone layer covers the entire earth and ...
What is ozone layer? »
            Have you ever worn a pair of glare glasses? In ...
How does climate change act on polar bears? »
            You must have seen pictures of the beautiful ...
Will global warming affect whales and dolphins? »
               While it is easy to comprehend the ...
How does global warming affect food security?»
                ...
How does deforestation affect global warming?»
            Have you heard that ...
How does global warming affect ocean currents? »
               We often think that the oceans are ...
What is the role of fossil fuels in global warming? »
               Many factors contribute to global ...
Is it true that global warming will predominantly affect islands?»
           It is beyond doubt that global warming will affect ...
Will global warming lead the human race to a disastrous end? »
               You must have heard the story of the ...
Will rising sea levels pose a threat to the world?»
            Global warming can bring ...
What are the causes of global warming? »
            Our planet is getting warmer and warmer as years ...
Where do the first signs of global warming appear?»
               Man has often considered nature to ...
Why is climate change an important issue? »
               Nature, like a mother, provides us ...
What is global warming? »
               Heat in summer can be troublesome. ...
What is acid rain?»
             Children generally love to play in the rain. ...
What are the effects of air pollution? »
              Clean air is the most vital aspect of ...
How can we prevent air Pollution? »
            Fresh air is probably the most important ...
How does pollution affect the oceans?»
            The vastness and volume of oceans often make us ...
What is pollution? »
               Recently, Delhi, our capital city, ...
What is population explosion?»
            Humans have dominated the world for thousands of ...
Did the industrial revolution cause the increase in the greenhouse effect? »
            The Industrial Revolution, which began in the ...
Why is the ‘greenhouse effect’ called so?»
                        ...
Does carbon dioxide make the climate warmer? »
              We have learned that humans inhale oxygen ...
How does climate change affect the land? »
            We have often heard our parents or eiders say ...
What is lithosphere? How does it influence other spheres? »
            The outermost part of Earth is where we live. Our ...
Why do climates change over time? »
                We know that there is no single ...
Is there a difference between climate and weather?»
            There may have been times ...
Does atmosphere have layers? »
                      Our atmosphere ...
Does atmosphere play a key role in the environment? »
              In the biting cold of a winter morning, we ...
Are lakes and ponds different from river?»
            There is a variety of water bodies on earth. They ...
Are rivers essential to the hydrosphere?»
            Civilizations world over have developed on the ...
Why are oceans important to our environment? »
            The deep blue seas have fascinated Man for ...
Are decomposers necessary in the biosphere? »
              Have you observed the carcass of an animal ...
Do food chains play an important role in biosphere? »
            If every living thing is comfortably placed in ...
Is life in biosphere cyclical? »
            Have you ever wondered whether we would run out ...
What is an ecosystem? »
            If you observe a pond or a river, you would be ...
What is ecology? »
            In the entire universe known to him, Man is yet ...
Why is biosphere vital to humans?»
            When Man goes into space, he needs protective ...
What is environment? »
            We tend to take our life for granted and think ...
Ageing»
What is a healthy diet for older people? ...
Ageing»
Can we help old people to have an active life? ...
Ageing»
Why do old people get shorter? ...
Ageing»
Why do people grow old? ...
Maintaining Health»
What is an antibiotic?                 ...
Maintaining Health»
Are all drugs dangerous?                 ...
Maintaining Health»
Why is smoking harmful?                 ...
Maintaining Health»
What is health?                   ...
Learning and Memory »
      What is a photographic memory?     ...
Learning and Memory »
  Are there different types of memory?         ...
Learning and Memory »
        What is conditioning?   ...
Brain Function»
  Are there special regions on the surface of the cerebrum?     ...
Brain Function»
Why does the brain have two sides?               ...
Brain Function»
        Which is the oldest part of the brain? ...
Brain Function»
What job does the brain do?                 ...
Genes»
      What are X and Y chromosomes?     ...
Genes»
      What is Down’s syndrome?     ...
Genes»
    What are chromosomes?         ...
Birth and Growth»
    What is a caesarean section?       ...
Birth and Growth»
        What is a baby like just before birth? ...
Birth and Growth»
    What happens after fertilization?       ...
Reproduction »
  What is a period?               ...
Reproduction »
How are sperms made?                   ...
Reproduction »
    What are the female sex organs?         ...
Chemical Control»
    Which gland helps with digestion?       ...
Chemical Control»
  What is diabetes?               ...
Chemical Control»
    Which is the ‘master gland’?       ...
Chemical Control»
    What job do hormones do?           ...
Body Defences»
How are invading germs destroyed?               ...
Touch, Taste and Smell»
  Why do hot foods taste better?           ...
Touch, Taste and Smell»
    How do pain-killing drugs work?       ...
Touch, Taste and Smell»
How does the sense of touch protect the body from injury?       ...
Body Defences»
    What happens if the immune system doesn’t work?   ...
Body Defences»
              ...
What is the immune system? »
What is the immune system? Unlike most of the other body systems, the immune system ...
Hearing»
  Why do I have wax in my ears? The ear canal is lined with cells that ...
Hearing»
What sounds can I hear? Sound is measured in decibels (dB).You can hear sounds ...
Hearing»
 What part of the ear is inside the skull? The delicate ear mechanism is ...
Eyes»
    How do the eyes focus?         ...
Eyes»
    What is colour blindness?         ...
eyes»
    How do I see in colour? The retina is packed with a layer ...
Eyes»
  How do my eyes work?             ...
Nervous System»
    What is a reflex? ...
Nervous System»
      What are nerve impulses like? ...
How are messages passed through the nervous system? »
How are messages passed through the nervous system?         ...
Nervous System»
What are nerve cells?                 ...
What is the nervous system?»
  The nervous system is made up of billions of tiny nerve cells that carry ...
Skin, Hair and Nails »
    What is acne?             ...
Skin, Hair and Nails »
    Why do I have nails?           ...
Skin, Hair and Nails »
  Why do I have hair?             ...
Skin, Hair and Nails »
   How does skin tan?             ...
Skin, Hair and Nails »
Why does the body have skin?               ...
BODY MAINTENANCE»
Why do people sweat?                 ...
BODY MAINTENANCE»
  What job do the kidneys do?             ...
BODY MAINTENANCE»
      How does the body keep itself working properly? ...
Digestion»
  What happens to food in the stomach?           ...
Digestion»
Why do I have different types of teeth?             ...
Digestion»
  Why do I need minerals and vitamins?         ...
Digestion»
    Why do I need food?           ...
Heart and Circulation»
  What keeps the heart beating?           ...
Heart and Circulation»
How does the heart work?                 ...
Heart and Circulation»
  What are blood vessels?             ...
Heart and Circulation»
What is blood?                Blood ...
Lungs and Breathing»
    Why should I breathe through my nose? ...
Lungs and Breathing»
    Why do I sometimes cough? ...
Lungs and Breathing»
Can I breathe out all the air in my lungs? Normally you only breathe out about 10 ...
Lungs and Breathing»
    How do I breathe? When you breathe, you draw air in ...
Muscles»
Why do many of my muscles work in pairs?             ...
Muscles»
How do muscle fibres shorten? Muscle fibres contain tiny rod-like structures that ...
Muscles»
      Which are the strongest muscles?     ...
Muscles»
What job do muscles do?                 ...
Skeleton and Joints»
  Can joints wear out?             ...
Skeleton and Joints»
    What are joints?             ...
Skeleton and Joints»
    Are bones alive?           ...
Skeleton and Joints»
        What are bones made of?   ...
Skeleton and Joints»
      Why do I need a skeleton?     ...
Body Basics»
      What are glands?       ...
Body Basics »
        What is metabolism?  ...
Body Basics»
    What are tissues? Millions of cells that do the same ...
Body Basics»
            What is the ...
Who were the Neanderthals? »
                      ...
Who were our first ancestors? »
Humans belong to a group of mammals called primates. It includes apes, monkeys and several ...
Where can we see dinosaurs? »
Most modern museums are very different from the early scientific exhibits of the 1800s. ...
Could a giant sauropod walk on its front legs? »
                        ...
How are fossils found? »
Fossils are usually first revealed by the process of erosion, or by quarrying. They are ...
When were the first dinosaurs discovered? »
Many people must have noticed old bones in the ground, but they did not attract much ...
How did dogs evolve? »
    Dogs appear to have evolved from small mammals such as the ...
How did animals survive the Ice Ages? »
                        ...
What were killer birds? »
                        ...
Did prehistoric sloths live up trees? »
                  Modern sloths are all ...
How did whales develop? »
             Whales evolved from sea lion-like ancestors ...
How did horses evolve? »
                        Animals ...
What was Chalicotherium? »
                  Although it was ...
What was a Glyptodon? »
                    This ...
What were sabre-toothed cats?»
                        ...
Which modern mammals are ‘living fossils’? »
                        ...
Which was the biggest mammal of all? »
                          ...
When did mammals first appear? »
                      ...
Can dinosaurs ever be re-created? »
                      ...
What other animals became extinct? »
                    The extinction ...
When did the dinosaurs die out? »
                        ...
Are there any living clues to the ancestors of birds? »
                        ...
Which fossils have been confused with Archaeopteryx? »
                  One recent fossil of ...
Which is the first known bird? »
                          ...
How small were some pterosaurs? »
Pterodactylus had a wing span 40 cm across. This means that it would have been a fast ...
How big were pterosaurs? »
As with most other extinct animals, new discoveries about pterosaurs are constantly being ...
What were pterosaurs? »
                          ...
Are crocodiles dinosaurs? »
                        ...
Did any ancient reptiles feed on shellfish? »
                        ...
What were ichthyosaurs? »
                    Ichthyosaurs are an ...
What were mosasaurs? »
                        ...
Which giant sauropod dinosaur was well able to defend itself? »
                        ...
Which theropod dinosaur was not a meat-eater?»
                      ...
Which dinosaur had a head like a bull? »
                    ...
Were dinosaurs an unsuccessful experiment in evolution? »
                        ...
Which dinosaur had a head like a parrot? »
                        ...
Which dinosaur had the largest claws? »
                        ...
Which plant and meat-eating dinosaurs had a crest all the way down their backs? »
                        ...
What was a Velociraptor? »
                        ...
How could small meat-eaters bring down large dinosaurs? »
                    Some smaller ...
Which remarkable ‘new’ dinosaur was found in 1983? »
                        ...
Which was the biggest meat-eater?»
                        ...
How did meat-eaters attack their prey? »
                          ...
What did meat-eating dinosaurs look like? »
                        ...
What were stegosaurs? »
                        ...
Why were ankylosaurs usually a match for predators? »
                          ...
Did dinosaurs have scales? »
                      The bodies of ...
Which marine reptile had the most flexible neck? »
                      ...
Which were the biggest marine reptiles?»
                        Pliosaurs ...
What were plesiosaurs? »
                          ...
How did slow-moving dinosaurs protect themselves? »
                     Plant-eating ...
Where did dinosaurs build nests? »
                        ...
Did different types of dinosaur nest together? »
                        ...
Did dinosaurs return to their nest sites? »
                        ...
What did dinosaurs’ eggs look like?»
                    Dinosaur eggs looked ...
Did dinosaurs have voices? »
                        ...
How long did dinosaurs live? »
                      ...
Did dinosaurs migrate? »
                        ...
How did the plant-eaters feed? »
                       The food ...
How did meat-eaters hunt their prey? »
                          ...
How might plant-eaters have defended themselves from attack? »
                      The ...
Did the dinosaurs live in groups? »
               Almost all modern grazing animals ...
How did sauropods digest their food? »
      We do not know what the structure of the sauropod ...
Did sauropods have any natural enemies? »
                        It ...
How were sauropods armoured? »
                    Most of the ...
Which was the tallest sauropod? »
                      ...
What happened to the Brontosaurus? »
                     Most ...
Which was the biggest sauropod of all?»
                    Scientists ...
Why did the sauropods have such a long neck and tail? »
                    The long ...
Did plant-eating dinosaurs stand upright? »
                        ...
Did dinosaurs have beaks?»
                        ...
What were sauropods?»
                     Sauropods ...
Which dinosaur behaved like a rhinoceros? »
                        ...
How small were some dinosaurs? »
                      Some ...
What was Iguanodon? »
                     Iguanodon was ...
Which dinosaur was bone-headed? »
                    The ...
Why did many dinosaurs walk on two legs? »
                   The hip bones of ...
How many different types of dinosaur were there? »
                       There ...
How do we know how dinosaurs moved? »
                    We can reconstruct ...
Were dinosaurs stupid? »
                      ...
Why did dinosaurs become so successful?»
                The main thing that distinguishes ...
What do we know about how dinosaurs’ bodies worked? »
                   Although dinosaur ...
What were dinosaurs?»
            Dinosaurs were reptiles ...
Which reptile had the longest neck? »
                        ...
What were archosaurs? »
                        ...
Reptiles or mammals? »
                      ...
What did early reptiles look like? »
                     Unlike the ...
Which were the first reptiles? »
                      ...
How do reptiles differ from amphibians? »
                       The ...
What are reptiles?»
                      ...
What are the modern amphibians? »
                      Frogs, toads, ...
What are amphibians? »
                        ...
What is a coelacanth?»
                        ...
Can fish breathe on land? »
                        ...
Why did fish come out onto the land? »
                     The ...
When did fish leave the sea? »
                      Around ...
What was the first form of life on land? »
                   Plants were the ...
What is the Burgess Shale? »
                        In 1909 ...
What was the largest shark that ever lived? »
                        ...
What did the first fish look like? »
                      ...
Which is the largest scorpion ever known? »
                       Among ...
What are trilobites? »
                     Trilobites are ...
What is an ammonite? »
Ammonites were members of the same class of animals as the modern octopus and squid. They ...
How did the Earth look in ancient times? »
                        The ...
Which ancient creatures may be the ancestors of modern animals? »
                   Animals such as ...
How is the Earth’s time broken up? »
                        ...
Did all the ancient life forms turn into the animals we see today?»
                 Evolution seems to have ...
Are there fossils of all extinct animals? »
                   The fossil record has ...
Do fossils prove evolution took place? »
                        ...
What can we learn from the fossil record? »
                       Since ...
How did life first appear?»
                       No one ...
Who first studied genetics? »
                     Gregor Mendel ...
What led Darwin to develop his theory of evolution?»
                      ...
How was the first rubber produced? »
                    Rubber is produced ...
Where did potatoes, maize and tomatoes come from? »
                          ...
What did Cuvier contribute to biology? »
                     Baron Georges ...
How has over-fishing affected the seas? »
                   Modern fishing methods ...
Where do tea and coffee come from? »
    ...
Which animals no longer live in the wild? »
                        ...
What are domesticated animals? »
                   There is a ...
How have we changed animals and plants?»
                      Most of the ...
Why is deforestation damaging the world’s ecology? »
                    The world’s tropical ...
What is the main crop grown on the prairies?»
                     The prairies in ...
Which are the main plants grown as crops?»
                        About ...
What lives on coral reefs? »
                   Coral reefs are the ...
What lives in deciduous forests? »
                        ...
What lives in tropical rainforests? »
                      Tropical ...
What lives in conifer forests? »
                       ...
Which communities live in the tundra? »
                  Tundra is the cold, partly ...
Which communities live in hot deserts? »
                   The plants and animals ...
What is a food chain? »
                      ...
What is ecology? »
                      ...
How can bugs make drugs? »
                      ...
How do we use microscopic forms of life? »
                    We use bacteria ...
Are viruses alive? »
                      ...
What are bacteria? »
                     Bacteria are ...
What is plankton? »
                        ...
What is an amoeba? »
                        ...
What are protozoa? »
                        ...
What lives in a puddle?»
                        ...
What have trees to do with making paper?»
                        ...
How are straight trees grown in order to make telephone poles? »
                     Trees always ...
What are bonsai trees? »
                        ...
Why don’t trees grow on top of mountains? »
                    ...
Which is the oldest tree? »
                      ...
How can you tell the exact age of a tree? »
                      Every ...
Can tree roots grow above the ground? »
                        ...
Which is the largest tree? »
                      ...
What is a conifer? »
                        ...
Why do plants sometimes wilt? »
                      ...
What are annual plants? »
                      ...
Why do leaves change colour in the autumn? »
                      ...
What are Perennial plants? »
                      ...
What are fertilizers? »
                      Fertilizers ...
How does water travel to the leaves? »
                   Water reaches ...
Why do shoots grow towards the light? »
                   Hormones called ...
How do roots find water? »
                Several outside factors ...
How does a seed grow? »
                  The embryo in a seed ...
How do mangroves stop their seeds from floating away?»
                      ...
How long can seeds survive? »
                      ...
How do animals help plants to spread their seeds? »
                      ...
Which is the biggest seed? »
                  The biggest seed is the coco ...
Can seeds fly? »
                        ...
What are seeds? »
                        ...
How are flowers pollinated? »
                        ...
What is pollen? »
                      ...
Why flowers are brightly coloured and scented? »
                      ...
What are the main parts of a flower? »
                        ...
Why do some plants have flowers? »
                        ...
Why fungi are usually found near trees? »
                     Sometimes ...
Are most toadstools poisonous? »
                      A few ...
What is a ‘fairy ring’? »
                A fairy ring is a circular pattern ...
What are fungi? »
                  Fungi used to be considered ...
What are lichens? »
                  Lichens are peculiar ...
How do ferns differ from flowering plants? »
                    Ferns differ ...
Which is the biggest kind of algae? »
                        Giant kelp ...
Which primitive plants are often found as fossils in coal? »
                      The ...
What are algae? »
                    Algae are the most ...
When did the first plants appear? »
                      ...
Can plants catch animals? »
                   Plants growing in bogs ...
How can plants store food and water? »
                      ...
Can plants move? »
                  Many plants are able to move ...
How can plants live in dry areas? »
                        ...
What are leaves for?»
                        ...
How do plants use sunlight? »
                        ...
How do plants survive cold weather? »
                        ...
How did plants lead to the appearance of animal life on the Earth? »
                        ...
What is a plant? »
                    ...
Do some animals return to their birthplace to breed? »
              Like migratory birds, there are many ...
How far can birds migrate? »
                The Arctic tern makes the ...
What is a locust swarm? »
                       For ...
Do insects migrate? »
                     Many ...
Where do swallows go in the winter?»
                ...
How do migrating animals find their way? »
                        ...
Do fish migrate? »
                        ...
Which mammals migrate? »
           Caribou and lemmings are migratory animals. ...
What is migration?»
    Migration is the mass movement of groups of animals.lt is ...
How can we study wild animal behaviour in the home? »
Although they have been domesticated for thousands of years, cats and dogs still retain ...
Why do some animals care for their young? »
Care of the young is important because it ensures that the young will grow up and be able ...
What is a pecking order? »
                   Among animals ...
What do cleaner fish do? »
                        ...
Why do some animals live in large groups? »
                  Predators usually live ...
How do scientists study animal behaviour? »
...
What are parasites? »
                 Parasites are animals ...
Which extinct giant animals were familiar to prehistoric humans? »
                  There is evidence ...
Are there still ‘wolves’ in Tasmania? »
There are no large marsupial predators living in Australia today, but the thylacine ‘wolf’ ...
What happened to the dodo? »
             The dodo was a large, flightless ...
Will whales disappear from the oceans? »
               All the larger kinds of whale ...
Does keeping pets threaten the survival of some animals? »
                    The desire of some ...
Why are turtles a threatened species? »
                      Turtles ...
Why do animals become extinct? »
                    According to the ...
Which is the largest invertebrate?»
            The giant squid is by ...
Why are starfish like sea urchins?»
    ...
Which animals make coral reefs?»
            Coral reefs are built up ...
How do jellyfish sting?»
    ...
Are any invertebrates intelligent?»
              The octopus ...
How long can a worm grow?»
      ...
How to cuttlefish and squid ‘talk’ to each other?»
            Cuttlefish and squid ...
Are all worms similar?»
            Most long, thin-bodied ...
What are invertebrates?»
              ...
How big can crabs grow?»
    ...
What is a crustacean?»
            Crustaceans are aquatic ...
How can flies walk on the ceiling?»
            The feet of a fly are ...
How do insects fly?»
            Insects have had 340 ...
What are insect larvae and pupae?»
            Insects such as ...
Are spiders insects?»
            Together with scorpions, ...
How do spiders make their webs?»
              Spiders spin ...
How does an arthropod grow?»
                ...
What are arthropods?»
            Arthropods are animals ...
Which is the most dangerous fish? »
Sharks kill several people every year, probably because they mistake swimmers for seals, ...
Which is the largest fish? »
    The whale shark is the largest living fish, commonly reaching 9 m ...
Can fish make electricity? »
Electric eels are well known, and they can stun their prey with a powerful shock. Other ...
Why don’t fish sink? »
                        ...
Can fish fly? »
  Flying fish are able to launch themselves above the surface of the water to ...
Where do fish live? »
    Fish have colonized almost every aquatic habitat and are found from ...
Can some fish breathe air? »
    Many fish that live in water containing little oxygen are able to ...
How can fish breathe underwater? »
  Fish are able to breathe underwater because they have special organs called ...
Which is the largest type of amphibian? »
    The giant salamander of Japan is a very strange-looking creature. ...
Are frogs and toads poisonous? »
  The skin of some frogs and toads contain poisons, which are among the most ...
Can amphibians live in dry deserts?»
                 The bodies of some frogs ...
How do amphibians reproduce?»
  Nearly all amphibians have aquatic larvae called tadpoles, which usually lead ...
Fatherly frogs »
Frogs and toads have developed some of the most unusual and varied forms of reproduction ...
Where do amphibians live? »
Most amphibians live in moist places near rivers, streams or lakes. They have thin moist ...
Which amphibian lives in caves?»
                      ...
What is an amphibian? »
    ...
Which reptiles live in the sea? »
                      ...
What is the biggest land-dwelling reptile? »
                   The largest ...
How long can reptiles live? »
                      ...
Which is the largest living reptile? »
                     The sea, ...
Which are the most poisonous snakes? »
               Every year about one million people ...
What is a tuatara? »
    The tuatara is a lizard-like animal, 70 cm long that lives only on ...
Why do some lizards lose their tails? »
                    Some types of ...
Do reptiles look after their young? »
                   Most reptiles lay ...
How do snakes move? »
                      Snakes have ...
What is a reptile? »
                     A reptile ...
How fast can birds fly? »
                      Most birds fly ...
Which is the most common bird? »
                     Some birds live ...
Which birds hardly ever land? »
                      ...
How far can birds fly?»
                      ...
Why do animals and plants have complicated Latin names? »
Most plants and animals have popular names that vary from place to place. Scientific names ...
Which is the smallest bird?»
                       The ...
Which is the largest bird? »
                    The largest living ...
How do birds fly? »
                  Birds’ bodies are very ...
Can all birds fly? »
                      Several ...
How are birds different from mammals? »
                       The ...
Which is the most successful mammal on Earth? »
                  We like to think that humans ...
Which is the largest land mammal? »
                      The ...
What is Parallel evolution?»
                          ...
Can mammals fly? »
                  Bats are the only mammals ...
Which is the smallest mammal?»
                      ...
What is a marsupial? »
                        ...
Do all mammals give birth to live young? »
                    True mammals all ...
What is a mammal? »
             Mammals are vertebrate animals ...
How do animals reproduce? »
                   Apart from some of the ...
How are animals related to each other?»
             The fossil record and modern studies on ...
Which animals are warm blooded? »
                 Mammals and birds are the ...
What are vertebrates? »
                     Vertebrates ...
What are the two main groups of animals? »
                   The animal ...
What is an animal? »
                 Animals are one of the major ...
Why is forestry important? »
               Trees are an important natural ...
How is coal formed? »
               Coal is formed from the compressed ...
What makes the snow leopard an endangered animal? »
               A snow leopard is a large cat that ...
Why is the sei whale an endangered animal? »
            The sei whale is one of the fastest whales in the ...
Why the Grevy’s zebra is considered an endangered animal?»
            The Grevy’s zebra is an important member of the ...
What makes the giant otter rare? »
               The giant otter is a carnivorous ...
Why the Rothschild’s giraffe is considered an endangered animal? »
            The Rothschild’s giraffe is a subspecies of ...
What makes the Iberian lynx special? »
               Iberian lynx is a wild cat native to ...
Why is the wild water buffalo rare? »
            The wild water buffalo is a large bovine native ...
Why is the Przewalski’s horse considered as an endangered animal?»
            The Przewalski’s horse is quite a strange name ...
Why is the green sea turtle considered as an endangered species?»
            Green sea turtles are ...
Why is the bonobo special?»
            The name bonobo many ...
Why is the hawksbill sea turtle a rare sight?»
            A hawksbill sea turtle ...
Why the red wolf is considered an endangered animal?»
            The red wolf or the ...
Why is the aye-aye special?»
            An aye-aye may not sound ...
Why is it said that chinchillas are endangered animals?»
            As adorable as their ...
Why is the golden lion tamarin special?»
            The golden lion tamarin ...
Why is the pygmy hippopotamus endangered?»
            Pygmy hippopotamuses, as ...
Why is the Asiatic cheetah a rare sight?»
            An Asiatic cheetah is ...
Why is the Chinese alligator considered as an endangered animal?»
            As their name suggests, ...
Why is the Borneo elephant different?»
            Believed to be the ...
Why is the African wild dog seen rarely?»
            African wild dogs are ...
What makes the gharial an extremely threatened animal?»
            Gharials are large ...
Why the proboscis monkey is considered an endangered animal?»
            The proboscis monkey is ...
Why is the black-footed ferret endangered?»
            The black-footed ferret ...
Why are Bornean orang-utans special?»
            Bornean orang-utans are ...
Why is the Amur leopard an animal to conserve for future?»
            Amur leopards are known ...
Why are Asian elephants under threat?»
            Asian elephants are ...
What makes the Mexican prairie dog an endangered animal?»
            As the name suggests, ...
What are the reasons behind the decline in the population of the Baird’s tapir?»
            As strange as their ...
Why is the Andean mountain cat special?»
            The Andean cat is ...
Why is the brown spider monkey considered as an endangered animal?»
            The brown spider monkey ...
What are the threats to Siamese crocodiles?»
            The name Siamese ...
Why is the Malayan tiger an endangered animal?»
            The Malayan tiger is a ...
What makes the dhole special?»
            The dhole is a wild dog found in Central, South, ...
Why is the black rhinoceros an endangered animal?»
            The black rhinoceros is ...
Why is the Sumatran elephant considered endangered?»
            Sumatran elephants are ...
Why is the Okapi different?»
            The okapi, which looks ...
What makes the Arabian tahr an endangered animal?»
            Arabian tahrs are the ...
Why is the white nosed saki in the endangered list?»
            The white-nosed saki is ...
Why is the purple-faced langur considered as an endangered animal?»
            The purple-faced langur ...
Why have the conservation programmes for the lion-tailed macaque resulted in a lot of public interest?»
            Lion-tailed macaques are ...
Why is it said that the Southern woolly lemur is special?»
             The Southern ...
Why is the Western lowland gorilla considered as critically endangered?»
            The Western lowland ...
Why is the common chimpanzee considered to be endangered?»
            Of course we have all ...
What makes the Northern quoll special?»
            A Northern quoll, or a ...
Why is a siamang special?»
            A siamang is a ...
Why is the West African giraffe a rare sight?»
            The West African ...
Why is the Asiatic lion in the IUCN Red List?»
            Asiatic lions are among ...
What makes the Bengal tiger an endangered animal?»
            The Bengal tiger or the ...
Why should the Siberian tiger be conserved?»
            The Siberian or the Amur ...
Why is a Tasmanian devil special?»
            Tasmanian devils are ...
What makes the red panda rare?»
            The red panda is a ...
Why is the Eastern lowland gorilla considered to be an endangered species?»
            The Eastern lowland ...
What is the IUCN Red List?»
            The International Union ...
What is meant by the term endangered?»
            Endangered, in its ...
What makes a saiga antelope an endangered animal?»
            The saiga antelope is a striking variety of ...
Why is a blue whale special? »
          Blue whales, as most of us know, are the largest animals ...
Why is the declining fin whale population a great cause of concern? »
            Fin whales are the second largest mammals in the ...
Why is the African wild ass rare? »
            By scientific classification, the African wild ...
Why is the addax an important animal? »
            The addax is a critically endangered desert ...
Why is the radiated tortoise an endangered animal? »
               A radiated tortoise is one of the ...
Why is it said that the numbat is an endangered animal? »
            A numbat is a rare marsupial animal that is ...
Why is the cottontop tamarin a rare sight?»
            Cottontop tamarins are small species of primates ...
Why is the Malayan tapir endangered?»
               The Malayan tapir is the largest of ...
Why is the Persian leopard special?»
               The Persian leopard is one of the ...
Why is it said that the red-headed vulture population is decreasing because of poisoning?»
                 Red-headed vultures, or ...
Why is the African grey parrot endangered? »
               The African grey parrot is one of ...
Why is the swift parrot rare?»
            The swift parrot is a fast-flying migratory bird ...
Why is the steppe eagle an endangered bird?»
            Like animals on land and water, birds in the sky ...
What makes the diademed sifaka rare? »
                   The diademed ...
Why is the geometric tortoise an endangered animal? »
            The geometric tortoise is one of the most ...
What makes Galapagos sea lions endangered animals?»
            The Galapagos sea lion ...
What are the specialities of the ring-tailed lemur?»
            The ring-tailed lemur is ...
Why is the Mediterranean monk seal so rare?»
               The Mediterranean monk seal is the ...
Why is the Nilgiri tahr endangered?»
           Nilgiri tahrs are stocky goats found on the ...
Why are mountain gorillas rare?»
            Mountain gorillas are ...
Why is the North Atlantic right whale considered to be endangered?»
            The North Atlantic right ...
Why is the sooty albatross an endangered bird? »
               Sooty albatrosses are a type of ...
Why is the African penguin rare? »
                African penguins are those ...
Why is the Spix’s macaw considered to be critically endangered? »
            A Spix’s macaw is one of the rarest birds in the ...
What makes the white-headed vulture endangered? »
            The white-headed vulture is a wild bird found in ...
Why is the Philippine eagle considered as endangered?»
          The Philippine eagle is the world’s largest eagle, found ...
Why is the California condor considered to be endangered? »
          California condors are among the largest flying birds in ...
What makes Galapagos penguins special? »
               The Galapagos penguins are the only ...
Why are the numbers of the Indian vulture declining?»
          Not many of us find vultures attractive or friendly. ...
What makes the blue-throated macaw rare?»
            The blue-throated macaw is a rare parrot that can ...
Why is the Madagascar heron special?»
            The Madagascar heron is a rare and large grey ...
Why the red-crowned crane is an endangered animal? »
          The red-crowned crane is one of the rarest cranes in the ...
What makes the Lear’s macaw a rare bird? »
            The Lear’s macaw is a large parrot endemic to ...
Why is the Malagasy pond heron an endangered bird? »
            The Malagasy pond heron is a migratory bird, seen ...
Why are the numbers of the Vietnamese pheasant declining? »
            The Vietnamese, or the Vo Quy’s pheasant, is a ...
When was coffee first grown?»
          A legend says the coffee plant first grew in Kaffa, a ...
When do people stop growing?»
               People stop growing when their bones ...
What is loam soil?»
          Loam soil is half way between clay and sandy soils. It ...
Why is the manchineel tree dangerous?»
The manchineel tree is dangerous because its sap and fruit contain poison. Its other name is ...
What is a Mudskipper?»
                        ...
Why do laurel and holly trees have shiny, waxy leaves?»
Laurel and holly trees have developed special kinds of leaves to seal the water inside them ...
Why is grass green?»
            The green colour in grass-and in most other ...
Why does bread have holes in it?»
            The holes in a piece of bread are made by bubbles ...
WHY IS DDT DANGEROUS?»
               After extensive us as a pesticide, ...
What is Photosynthesis?»
            Photosynthesis is the process by which green ...
Why are vampire bats dangerous?»
          Vampire bats are dangerous because they carry rabies and ...
Where would you find a red Giant?»
            You would find a Red Giant on the Sierra Nevada ...
What are fossils?»
          Fossils are the remains, moulds, traces or ...
Where would you find a trap-door spider?»
Trap-door spiders are to be found just under the surface of the earth. They belong to the ...
Why do birds have different bills? »
The shape of a bird’s bill or beak is closely related to the kind of food it eats and the ...
When does a tadpole become a frog?»
Frogs’ eggs become tadpoles within two weeks of being laid in the water, but tadpoles may ...
What are termites?»
Termites are soft-bodied insects belonging to the family Isoptera. They are sometimes ...
Where are the largest animals found?»
Blue whales are the largest living animals. They are cosmopolitan creatures and are found ...
Why do flowers have sepals?»
The sepals of a flower protect it while it is in bud. The flower is really a kind of shoot, ...
What is the coccyx?»
    The coccyx is the lower end of the spinal column of man and ...
Where did all the dodos go?»
The dodo was rather a stupid bird. Indeed, it was so stupid that it was named dodo by the ...
Why are some Japanese trees minutes?»
    Many Japanese trees are small because they are dwarfed by the ...
When did Pterodactyls live?»
Pterodactyls (or pterosaurs) lived between 150 million and 70 million years ago. These ...
What do birds of prey eat?»
Birds of prey are those that feed wholly or mainly on meat taken by hunting. They catch ...
Where does a bee keep its sting?»
A bee keeps its sting at the end of its abdomen. At the tip of a bee’s abdomen is a shaft ...
Why do most fish have scales?»
Fish have scales as a protective coating for the skin. In fact, not all fish have them. But ...
What is a greenshank?»
A greenshank is a little bird with a long beak and olive-green legs-a member of a group of ...
Where would you find live prehistoric fish?»
Numerous fossil remains have been found of coelacanth fish which died over 70 million years ...
Why do bats make high-pitched sounds?»
Bats use high-pitched sounds to find their way about. They are nocturnal animals. That is ...
When were breakfast cereals first used?»
Cereals, of course, in the general sense, including wheat, rice, maize (known as corn in ...
Who uses a Cardiac pacemaker?»
Cardiac pacemakers are used by sufferers from “heart-block”. They do the work normally ...
What is muscle?»
Muscles are the body tissue which, because it has the power of contraction, enables the ...
Why do we sleep?»
Some scientists consider that sleep is an instinct, a basic need for the body and mind to ...
When were contact lenses invented?»
The first contact lenses were made by A.E. Fick in 1887, but were not successful. During ...
How do we grip?»
We take a grip on things by using our muscles to exploit the development of the human ...
What is the umbilical cord?»
    Inside the womb of a pregnant woman or animal a placenta is formed, ...
Where would you catch malaria?»
The most likely places to catch malaria would be in tropical and sub-tropical countries, ...
What makes you feel dizzy?»
Dizziness most commonly occurs when a person who has been moving around with speed stops ...
Why do doctors take your temperature?»
The body temperature of a human being is an indication of his physical condition, so that ...
When does blood congeal?»
Blood congeals when a part of the body is wounded. If it failed to congeal the injured ...
Why do we become sea-sick?»
We become sea-sick because our balancing organs, the labyrinthine portions of the inner ...
What does an X-Ray show?»
X-Rays are electromagnetic rays of very short wavelength which can penetrate matter through ...
When do doctors give electric shocks?»
  Electric shock treatment, or electroconvulsive therapy, is sometimes used with ...
Why do we have brains?»
The brain directs and coordinates movements and reflexes, registers sensations and is the ...
How is paper made?»
A sheet of paper consists of vegetable fibers of different sizes, twisted and intertwined ...
Why is pollution a problem?»
Pollution is a problem because man, in an increasingly populated and industrialized world, ...
Why are fertilizers used on farms?»
Fertilizers are used on farms to increase crop yields by ensuring that soils contain the ...
Why can Owls see well at night?»
The night vision of Owls is 100 times as keen as that of human beings, because their eyes ...
When does an atoll start to form?»
    An atoll or coral reef begins to form when tiny marine animals called coral ...
Why do some plants capture insects?»
               Some plants capture ...
Where does a leech feed?»
      Leeches, which are rather slimy worms and vary in length from an inch ...
What is a loofah?»
A loofah is a fibrous, cylinder-shaped vegetable product often used in bathrooms as a kind of ...
Where does the breadfruit tree grow?»
      The breadfruit tree is found in the South Pacific Islands and, to a ...
Why yews are often found in churchyards?»
     Yews have long been associated with religious worship. So it is likely ...
What is a salamander?»
A salamander is amphibian-an animal that lives both on land and in the water. It is a ...
Where do flies go in the winter?»
          During winter flies will hibernate ...
When does a hermit crab change its shell?»
      A hermit crab changes its shell when it has grown large enough to need ...
Why so we have a dawn chorus?»
          The song of the birds at dawn has given pleasure to ...
Why do some elephants have very large ears?»
          African elephants have larger ears than Indian, or ...
When does a chameleon change colour?»
            A chameleon will change color when it senses ...
Where do Elephants go to die?»
          Group of elephants have been found buried together both ...
When do bees swarm?»
             Bees swarm in late spring in search of new ...
How do frogs breathe under water?»
               Under water, frogs breathe through ...
When is a butterfly formed?»
            A caterpillar starts to become a butterfly as ...
Why do many flowers have a sweet scent?»
The sweet scent of flowers is designed to attract insects who seek food in the shape of ...
What is reindeer moss?»
Reindeer moss is a species of lichen so called because it is the staple winter food of ...
Where was the first Zoo?»
    The first zoo was formed in China in the 12th century B.C. But it ...
When do birds migrate?»
Million of birds of many different varieties migrate at the end of summer. With unfailing ...
Fossils »
  What are fossils? Fossils are the traces of ancient animals and plants ...
INTRODUCTION – PLANET EARTH»
Planet Earth is our home. It is also home to millions of different plants and animals. Like the ...
CHANGING EARTH»
The remains of ancient animals, or ‘fossils’, tell us that our planet and the life on it were ...
ROCKS AND EROSION»
  Rocks are not as permanent as they seem. Rain, wind and freezing weather ...
RICHES OF THE EARTH»
All the metals we use are taken from the Earth. Most of them are found in rocks, combined with ...
CLIMATE»
Different parts of the globe have very different climates. It gets hotter as you travel ...
THE ATMOSPHERE»
        The air you breathe forms a thin layer ...
EARTH’S BALANCE»
The parts of the world affecting our lives are called the ‘environment’. This includes the ...
MORE ABOUT PLANET EARTH»
Moving Crust As the plates of the Earth’s surface move towards each other, one plate ...
LIVING THINGS - INTRODUCTION»
    Our world is home to many millions of living things. From the ...
IS IT ALIVE?»
Imagine you were looking at a waxwork model of a child. They model might confuse you at ...
THE VARIETY OF LIFE»
There are about two million different types of living things today! Although they share similar ...
EVOLUTION»
Where did all the different types of living things come from? Nobody knows for certain, but ...
CELLS»
All living things are made up of tiny building blocks called ‘cells’. Cells are too ...
FEEDING AND BREATHING »
Living things need certain substances to move, grow and keep themselves alive. Animals eat ...
GETTING FROM PLACE TO PLACE»
Most animals have to move to find their food and to avoid predators and other dangers. Many ...
A CHANGING ENVIRONMENT»
  In order to survive, living things must be able to detect changes in their ...
REACTING TO CHANGE»
When we react to a changing environment, conditions inside our bodies change. Your ...
PLANTS AND ANIMALS - GROWTH AND REPRODUCTION»
    As plants and animals develop, they grow and get larger and ...
ANIMALS COMMUNICATING»
Many living things can pass information to each other – they ‘communicate’. The expression on ...
LIVING WITH EACH OTHER»
A living thing cannot live alone. It depends on the other living things to supply the materials ...
MORE ABOUT REPRODUCTION»
  Genes and chromosomes Inside the nucleus of a human cell are 23 pairs of ...
Different seashores»
      There are different seashores all over the world. ...
Seashore plants and animals hold on tight»
The waves that crash on to a seashore are very strong. Seashore plants and animals must hold on ...
Seashore Shells»
      Shellfish are small animals that live inside ...
Life in a rock pool»
    When the tide goes out, some water is left behind in hollows in ...
Seashores animals - Digging in»
      Many seashore animals bury themselves in the sand, ...
Seashore plants»
    Many plants live on the seashore. Seaweeds are seashore plants ...
Seashore birds»
    Seashore birds feed on different foods. They hunt for food on ...
Seashore Fishes»
      At low tide, seashore fish hide. They squeeze into ...
Seashores visitors»
    Some of the animals that we see on seashore do not live there ...
Looking after the seashore»
      Seashores can be harmed by people. If we leave ...
Rescuing the rainforests»
Rainforests are important to all of us, so we must save them. Many groups of people ...
Rain forests Homes under threat»
    People who live in rainforests know how to find everything they ...
Rainforests - The Earth’s lungs»
Rainforests only cover a small part of the Earth’s surface but they are sometimes called the ...
Rain forest Nature’s superstore»
Many of the things that we use and eat every day come from the rainforest. New animals and ...
Rainforest recyclers»
    The rainforest floor is covered with a thick layer of fallen ...
Life at ground level in rainforest»
  The forest floor is the darkest and warmest part of the rainforest. Very ...
Understory gloom»
  Leafy bushes and small trees make up the understory. It is dark, hot and ...
High flyers Birds in tropical rainforests»
      One-fifth of all the birds in the world live in ...
Treetop life »
      Plants and animals crowd the treetops. Some plants ...
Rainforest trees»
    Trees grow fast in the warm, wet rainforest. They race each ...
Inside a rainforest»
      The heat and heavy rain in a rainforest are perfect ...
What are rainforests?»
    Rainforests are dense, warm, wet forests, with huge trees. They ...
Flesh - eating plants»
        Some plants trap insects and suck the ...
Plants as food»
  People and animals need plants for food. We can eat all the different parts ...
Seeds life Cycle»
When a seed bursts into life and a new plant begins to grow, it is part of a greater life ...
When seeds begin to grow»
        A seed needs water and warmth so it can ...
How seeds travel»
Most new plants will grow better if they do not have to share water, soil and sunlight with a ...
Seeds»
      Some seeds are so tiny they look just like specks ...
Flowering trees»
  Some trees have two kinds of flowers on them – male flowers and female ...
Flower needs birds»
  Some flowers need birds to help them make seeds. Just like insects, some ...
Flowers Colour and scent»
    Some flowers have brightly coloured petals. When bees and other ...
Making seeds»
    To make a seed, pollen has to go from the male part of one ...
The parts of a flower»
Flowers open out from buds in spring or summer when it is warm and light. Sepals on the buds ...
Flowers are everywhere»
  Flowers are many shapes, sizes and colours. Some are big and colourful. ...
How do plants breathe?»
    Most living things need air to live. You cannot see the air, ...
How do plants feed?»
  Plants make their own food. They do this in the green parts of their ...
Making new plants»
    Most plants have flowers so they can make seeds. There is a new ...
Where do plants live?»
Plants grow all over the world. They make the best use they can of the soil, water and ...
Plant survival»
      Plants can live almost anywhere. They live in dry ...
Trees »
    Trees are the biggest plants of all. There are three kinds of ...
Grasses»
      Grass plants grow all over the world. Some grasses ...
Moss, lichen and fungus»
      Mosses, lichens and fungi do not have flowers. ...
Plant protection»
  Many plants cannot grow or make seeds if their stems and leaves have been ...
How do plants drink?»
      All living things need water. Plants drink by ...
Plants are living things»
      Plants need sunlight, air and water. Most plants ...
The plant world»
Some plants are so small they are hard to see. Some are so big they seem to touch the sky. ...
Wood for the future»
  Wood is a valuable material that is used every day all over the world. ...
Wood for life»
    Trees are very important for all the life on Earth. They help ...
Wood for animals»
      Many animals use wood. Some use it as a building ...
Paper – making »
      Most of the conifer trees grown in plantations ...
Wood for medicine and food»
    Many of the foods and medicines we use come from rainforest trees ...
Wood for fuel »
    Many people all over the world use wood for burning. Wood is a ...
Wood Work»
      Wood is a very useful material and is used to make ...
Trees cutting and moving»
    After the trees are cut down they are taken away. Most logs are ...
From seed to timber»
    Most of the wood we use is specially grown in large forests. These ...
Wood close up»
      Each year a tree grows a new layer of wood. The rings ...
Wood from trees»
  The wood we use comes from two types of trees. One type is called ...
What is wood?»
      Wood is an amazing natural material. It is used ...
How does wool keep us warm? »
               There are about 950 million sheep in the ...
Why is it difficult to see things immediately when we enter a dark room? »
               It is a matter of common experience ...
Why does milk spill out when boiled? »
                 When milk is heated it ...
What is First Aid? »
               Accidents are part of our lives. ...
Why are some deserts getting bigger? »
                About one third of the world’s ...
Why the cotton plant is called Daughter of the Sun? »
               The ancients called the cotton plant ...
Who’s brighter: Girls or Boys? »
               There is a difference of opinion on ...
What is Osmosis? »
               It is a well known fact that when ...
How is wax made? »
            Wax is an insoluble solid fatty substance that is ...
Which fish spits at insects? »
               Fishes are the most numerous among ...
How do plants protect themselves from frost? »
            There are over 350,000 kinds of plants in the world. ...
How do different animals move? »
There are millions of animals found on earth that moves about in hundreds of different ...
How do animals release their tension? »
          Sometimes animals are caught in such a situation that they ...
How do living beings adapt to their environment? »
               Adaptation is a biological term which ...
Which animal can see with its eyes closed? »
               There are about 2000 lizard species ...
Which is the largest seabird? »
               Albatross is the largest flying ...
Where do crabs climb trees? »
               It is established by the scientists ...
Why do dogs pant in summer? »
               A dog, like a cow, an elephant, or a ...
Why do flowers of Raat Ki Rani bloom only at night? »
               Many animals and creatures rest ...
Does any animal have three eyes? »
               Tuatara or Sphenodon punctatus is ...
Where is cocoa grown? »
               Cocoa originated in Central and ...
Which are the largest and smallest flowers? »
               In the world of nature we see a great ...
Which is the most beautiful reptile? »
               There are about 5000 species of ...
Do snakes love music? »
               All of us have seen snake charmers ...
Why do trees change colour in autumn? »
               On the basis of autumn defoliation ...
Why do animals have a tail? »
            All vertebrates except man have a tail. According ...
What is appendicitis? »
               The appendix is a part of the ...
What causes an itch? »
               We are all familiar with the itching ...
Does everybody have a different smell? »
               The police dogs can identify the ...
Does our body generate electricity? »
          We all have heard of fishes producing electric currents but ...
What are the functions of the pancreas? »
               The pancreas is an important organ ...
What is Electromyogram? »
               There are over 600 muscles arranged ...
How is artificial insemination done? »
            Insemination, which means the injecting of sperms ...
What causes ringworm? »
               Ringworm is a common skin disease. ...
How is fluoride useful to our teeth? »
               We have two sets of teeth during our ...
What are hereditary diseases? »
               Some diseases pass on from one ...
Why do our hands and lips get chapped in cold days? »
              Our skin is one of the largest functional ...
How is vision tested? »
               When we see an object the light ...
What causes influenza? »
            Influenza is a common ailment caused by different ...
What is genetics? »
          Genetics is the science of heredity, dealing with ...
Who discovered vitamins? »
               It is well known that vitamins are ...
What is ecology? »
          Our lifecycle is closely related to ecology. Austrian ...
Why do we see stars when hit on the head or eyes? »
            It is a matter of common experience that we see ...
Why do we feel pain? »
               Pain is an unpleasant feeling that ...
How are cells, tissues, organs and systems formed in the body? »
          We know that construction of a huge structure requires ...
Does our body have a built-in-clock? »
            When we decide to get up early in the morning at ...
What is arthritis? »
               Arthritis is the name given to a ...
Why do we belch? »
          After taking meals most of us tend to belch. Some people ...
What is electroretinogram? »
          The recording of potential changes produced by the eye when ...
Which substances work as fuel in our body? »
          Just as an engine needs fuels like coal, petrol etc. to ...
What is consciousness? »
               The word consciousness in ...
What is cholesterol? »
          Cholesterol is an organic compound belonging to the steroid ...
Why is the Asian koel unique?»
            The Asian koel is better known by its voice ...
What are the features of the Indian cuckoo?»
            The Indian cuckoo is a medium-sized bird found in ...
What are the differences between the common myna and the bank myna?»
The common myna and the bank myna are different in many ways. The common myna is ...
What are the features of the wire-tailed swallow?»
            The most notable feature of a wire-tailed swallow ...
What makes the house sparrow unique?»
               The house sparrow is unique, because ...
Why is the tailor bird so called?»
            As the name suggests, the tailor bird is a ...
Why is the red-vented bulbul considered as a common bird?»
            The red-vented bulbul is the most common variety ...
What are the features of the Indian robin?»
               The Indian robin is a very familiar, ...
Why is the Eurasian collared dove different?»
            The Eurasian collared dove is a medium-sized ...
What are the features of the laughing dove?»
          The laughing dove is a small, thin bird with a brown and ...
What are the features of the spotted dove? »
            The spotted dove is also known by various other ...
Why is the blue rock pigeon one of the most familiar birds? »
          The blue rock pigeon is a common bird, as familiar as a crow ...
What are the features of the black-headed jay?»
The black-headed jay is a lean, light-pink coloured bird with a black head and a thick, ...
What are the features of the Indian tree pie? »
          The Indian tree pie is a small bird, with mainly chestnut ...
What makes the common raven a familiar bird in India?»
            The common raven is a large bird found in dry or ...
What are the features of the large-billed crow? »
               The large-billed crow has a glossy ...
Why is it said that the Indian house crow is abundantly found, not only in India, but worldwide? »
            The Indian house crow is perhaps the most ...
What are the specialities of the plum-headed parakeets? »
          Plum-headed parakeets are notable for the distinct ...
What are the features of the Alexandrine parakeet?»
            The Alexandrine parakeets were once considered ...
Why the rose-ringed parakeet is considered special?»
          The rose-ringed parakeet which is also called the ...
What are the features of the white-spotted fantail flycatcher?»
             The white- spotted fantail flycatcher is a ...
What makes the Nilgiri flycatcher unique?»
                 The Nilgiri ...
Why is it said that the Tickell’s blue flycatcher is a common bird?»
          The Tickell’s blue flycatcher is named after Samuel ...
Why is the Grey-headed canary flycatcher unique?»
          The grey-headed canary fly-catcher is a very small bird, ...
What are the features of the rufous woodpecker?»
            The rufous woodpecker is a medium-sized bird ...
Why is the heart-spotted woodpecker different from other woodpeckers in India?»
          The heart-spotted woodpecker is often detected by its ...
What are the special characteristics of the Indian spotted creeper? »
               The Indian spotted creeper is a tree ...
Why is the chestnut-bellied nuthatch a prominent nuthatch in India? »
            The chestnut-bellied nuthatch is a small, ...
What makes the velvet-fronted nuthatch different from a woodpecker?»
          A nuthatch is what we call a small songbird with a ...
Why is the common flameback a special bird?»
            The common flameback is a kind of medium-sized ...
What are the features of the black-rumped flameback?»
               The black-rumped flameback is a very ...
Why is it said that the Yellow-crowned woodpecker is a common bird in India?»
                 The yellow crowned ...
Why is the stork -billed kingfisher different from other kingfishers?»
          The unique features of the stork-billed kingfisher are ...
Why is the whiskered tern a popular bird in India?»
The whiskered tern is a common bird in the northern regions of India, like Jammu and ...
What are the features of the Indian skimmer?»
          The Indian skimmer is a large bird, around 40 cm in length ...
Why is the pied kingfisher unique?»
          The pied kingfisher is also a very familiar type of ...
Why is the common kingfisher a popular fish hunter?»
            Who hasn’t seen a kingfisher that clean little ...
Why is the white ibis said to be prominent among the ibises in India?»
            The white ibis is a large bird which is as large ...
What are the characteristics of painted storks? »
               The painted stork got its name from ...
Why is the yellow bittern said to be a fish hunting bird?»
The yellow bittern is a very small heron, with a feather cover in black and dull, dark ...
Where can we find purple herons? »
            The purple heron is a large bird with a gracefully ...
Why is the black-crowned night heron unique?»
            The black-crowned night heron’s name is self ...
Little Owl »
            The little owl is a small owl ...
What are the features of the Indian pond heron?»
            The Indian pond heron is a very popular bird ...
What are the features of the grey heron?»
          The grey heron is a large grey or black coloured heron ...
Why is it said that the little heron is a popular species in India?»
            The little heron is a small, dark heron very ...
What are the features of the intermediate egret?»
            The intermediate egret is also a snow white bird, ...
Why is the great egret known as a common bird in India?»
               The great egrets are very common in most ...
What are the special features of the little egret?»
          The little egret is a very common kind of heron, found ...
What are the specialities of the savanna nightjar?»
          The savanna nightjar is not a single kind of bird, but a ...
Why is it said that the jungle nightjar can be seen in most parts of India?»
          The jungle nightjar or grey nightjar is a kind of ...
Why is the Sri Lanka frogmouth unique?»
                The Sri Lanka frogmouth is a ...
What are the features of the large-tailed nightjar?»
               The large-tailed nightjar is a ...
Why is it said that the Indian nightjar is a one common bird in India?»
            The Indian nightjar is a very common bird in ...
Why is the jungle owlet special among the nocturnal birds of India? »
            The jungle owlet is a small bird, with yellow ...
What are the features of the rock eagle-owl?»
          Rock eagle-owls are very big birds found only in the Indian ...
Why is the spotted owlet so called? »
          Spotted owlets are very familiar to humans, who ...
Why the collared scops owl is considered a common owl in India? »
            The collared scops owl is a brownish or greyish ...
What are the characteristics of the barn owl? »
          The barn owl is the most commonly found variety of ...
What makes the peregrine falcon or shaheen unique?»
          The most remarkable characteristic of the peregrine ...
Why is the red headed merlin an unusual bird? »
          The red headed merlin is a kind of falcon which is ...
What are the characteristics of the Bonelli’s eagle?»
     The Bonelli’s eagle is a large bird of prey, found on hilly and ...
Where can we see tawny eagles?»
          The tawny eagle is a large bird of prey, typically around ...
Why is the shikra different from other birds?»
          The shikra is a little killer! It is a bird of prey ...
What are the unusual features of the crested serpent eagle?»
           The crested serpent eagle is a large bird of prey, ...
What are the features of the Indian vulture? »
          The Indian vulture is also called the long-billed ...
Why is it said that the White-rumped vulture is useful to humanity?»
               The white-rumped vultures help us by ...
What are the special characteristics of Egyptian vultures?»
            The Egyptian vulture does not look much like a ...
Why is it said that the black shouldered kite is similar to the owl in appearance?»
                  The black shouldered kite ...
What are the features of the Brahminy kite?»
          Brahminy kites seen in most parts of India have a striking ...
Why is the black kite popular?»
               Black kites are very familiar to ...
What are the characteristics of the little grebe?»
            The little grebe also called the dabchick is a ...
Why is the large cormorant so called?»
          The large cormorant or the great cormorant is a ...
What are the special features of the little cormorant?»
            The little cormorant is another fish-loving bird ...
What are the special characteristics of the Indian darter?»
          What if a bird has a long, thin, snake-like neck that can be ...
Why the lesser whistling is duck much popular? »
          Have you ever seen a duck whistling at a high pitch? ...
What makes the comb duck special? »
           Comb ducks are large ducks with black bills. The males ...
What are the main features of the spot billed duck?»
          A spot billed duck is a duck with spots on its bill. It ...
What are the special features of the cotton pygmy goose? »
          The cotton pygmy goose is a small, duck-like bird. ...
What makes the rain quail a unique bird? »
            Rain quails are small birds seen across India, ...
Why is it said that the jungle bush quail and the common quail are different in appearances?»
                      ...
What are the special features of the grey partridge? »
          Grey partridges are very common in India, except in the ...
What are the main characteristics of black francolins?»
            Black francolins are medium-sized birds, found ...
Why the Himalayan monal is considered a beautiful pheasant?»
          The Himalayan monal is a showy large bird with brilliant ...
What makes the cheer pheasant unique?»
               The most important thing about cheer ...
What makes the Kalij pheasant one of the most familiar among Himalayan pheasants? »
          Kalij pheasants are distributed around the foothills of ...
What are the characteristics of grey jungle fowls? »
          Grey jungle fowls are very common in states like ...
What makes the red jungle fowl unique?»
                Red jungle fowls are the ancestors ...
What are the characteristics of the peafowl? »
          The name peafowl brings to our mind the picture of a ...
What are goose pimples? »
          It is a matter of common experience that when we feel ...
How does a human baby grow inside its mother’s womb? »
            Sexual reproduction is a naturally gifted process ...
When did the first human heart transplant take place? »
          The scope of heart surgery has vastly increased ever since ...
How is sunlight beneficial for us? »
It has been scientifically proved that sunlight has several medicinal values that help in the ...
What is jaundice? »
            Jaundice is a disease of the liver in which the ...
What is electroshock therapy? »
          Electroshock therapy is a method of treating certain ...
What is the Rh factor? »
            The term ‘Rh factor’ stands for Rhesus factor. In ...
What is cirrhosis of the liver? »
            Cirrhosis is a liver disease which renders a part of ...
How does our nervous system function? »
           The nervous system is a network of nerve cells ...
What is anaemia? »
          Anaemia is a particular physical condition in which the ...
Why do we have a belly button? »
          Belly button is the little dent that we have in the ...
Why do we get ‘Pins and Needles’? »
‘Pins ins and Needles’ is referred to the tingling sensation we feel in our hands, feet, ...
What are the different methods of birth control? »
          The potential threat of a population explosion made family ...
Why do we shiver on a cold day? »
            It is a matter of common experience that we shiver ...
What is Electroencephalography (EEG)? »
          EEG is the abbreviated form of electroencephalography ...
What are emotions? »
            Emotion can be described as an excited state of mind ...
What causes a reflex action? »
          A reflex action is an automatic nervous action in which a ...
What are tranquillizers? »
          A tranquillizer is a drug that calms a person’s mind. It ...
Why is it said: An apple a day keeps the doctor away? »
          The age-old maxim, ‘An apple a day keeps the doctor away’ ...
What is Extrasensory Perception? »
            In our day-to-day life we often come across ...
What is a rain forest? »
          A rain forest is a warm and rainy place with a thick growth ...
What are pesticides? »
            Any plant or animal that occurs in such abundance ...
What is Bonsai?»
          Bonsai is the art of developing and growing dwarf trees. ...
What is the Food Chain? »
               The ‘food chain’ is defined as the ...
Why are crocodiles so dangerous? »
          A crocodile is a large reptile with a long cigar-shaped ...
How is Nightingale distinct from other birds? »
               In the kingdom of birds, nightingale ...
How do plants and animals defend themselves? »
                    Almost every plant and ...
Which animals are extinct now? »
               The study of the fossils has revealed ...
Which animal spends its life upside down? »
               There is a family of mammals called ...
How did different plants get their names? »
          Ever since the evolution of languages different plants and ...
Who is called the king of fishes? »
               Just as lion is called the king of ...
Which are the birds of prey? »
The birds which feed on other animals are called the birds of prey. They catch and feed on ...
How do the fishes smell things? »
          It may be surprising to note that fishes can smell things ...
How do the plant seeds get dispersed? »
               One of the major differences between ...
How did the first bird evolve? »
            It seems strange but true that the first species of ...
Why are stripes a boon to the zebras? »
            Zebra is a member of the horse family. But as ...
Which fish keeps its eggs in its mouth? »
          There is a peculiar species of sea-fish that keeps its eggs ...
Can a scorpion kill a man? »
Scorpions are small insect-like creatures that belong to the class arachnids. They live in ...
Which lizard squirts blood from its eyes? »
                    Lizards are mostly found ...
Does any bear wear ‘glasses’? »
            The kingdom of animals has always been a source of ...
Why do birds sing? »
               The twittering of birds usually ...
Which birds cannot fly? »
            There are several species of birds on earth which ...
Can the fishes hear? »
               The most surprising fact about fishes is ...
Which insects swim upside-down? »
                There are certain peculiar types of ...
Why do cats purr? »
                    When a cat wants to ...
How do some animals recognise their offspring? »
               It is said that only man has highly ...
How do we study the internal structure of plants? »
                          ...
Why do plants and animals become extinct? »
                    When Darwin ...
Can one tree produce the fruit of a different tree? »
            An affirmative reply to this question is amazing ...
Do some plants also move? »
               One of the fundamental differences ...
How do human beings make sound? »
               From the very moment of birth, we, ...
Why do woollen clothes kept in boxes get holes? »
          Most people think that holes in woollen clothes are made by ...
What are proteins? »
          Proteins are very important chemical compounds contained ...
When were anaesthetics first used in operations? »
          Before the discovery of anaesthetics, an operation used to ...
Why are head injuries dangerous? »
In times of war, soldiers use special helmets to protect their heads. While driving a scooter, ...
What is typhoid? »
          More than 60 years back typhoid epidemics used to claim ...
Why do babies cry so much? »
          In fact, crying is the baby’s first sound message. It is the ...
Why do doctors examine the pulse? »
          When a person falls sick, the doctor often examines his ...
What are enzymes? »
            The human body is a machine that needs energy to ...
Why do some people stammer? »
          The biological process of speech requires the amazing ...
What is blood pressure? »
          The heart is a vital organ that pumps blood to different ...
Why do some people have a squint? »
          A squint is a physical defect in which both eyes do not ...
What is the Iron-lung machine? »
          The iron-lung machine was one of the earliest ...
What causes asthma? »
          Asthma is a chronic disease of the lungs in which a person ...
What is physiotherapy? »
          Physiotherapy is that branch of medicine which makes use ...
Why are infants kept on milk? »
          The first kind of food a baby gets is mother’s milk. Why is ...
What are the functions of arteries and veins in our body? »
Blood must reach every cell in the body to provide it with food and oxygen, and to remove waste ...
What is electrocardiography? »
          Electrocardiography is a system of tracing graphically, the ...
Why don’t people have identical voices? »
          No two persons in the world have exactly the same voice! Do ...
What causes leprosy? »
            You must have heard of the great service, Mother ...
What is the function of liver in our body? »
          The liver is a large and vitally important organ in the ...
What is chicken pox? »
          Chicken Pox is a contagious disease that mostly affects ...
What do we mean by right-eyed or left-eyed people? »
We all know whether we are right-handed or left-handed. But only a few of us know whether ...
What is allergy? »
          Hay fever, rashes on the skin, reactions to certain ...
What is blood cancer or leukemia? »
          Leukemia or blood cancer is a fatal disease of the ...
Which are the different joints in our body? »
           The place where two or more bones meet in the body is ...
What is albinism? »
          Albinism has been derived from the Latin word ‘albus’ which ...
How do urine tests help in diagnosis of diseases? »
          Diagnosis of different diseases by urine examination has ...
What happens in our brain? »
          Normally mammals have bigger brains in relation to their ...
What is immunity? »
          Immunity is described as the ability of the body to resist ...
How are hard drinks made? »
          Wine is probably the first type of hard drink to have come ...
What is a Mass Spectrograph? »
               A mass spectrograph is an instrument ...
Where do penguins live? »
               Penguins are a peculiar category of sea ...
How can dogs be dangerous to us? »
          It has often been said that a dog is a man’s best friend. In ...
Which are the large-sized flying birds? »
               The largest of all living birds is the ...
Why do flies rub their legs together? »
            Fly is a two-winged insect that has some 90,000 ...
Which is the world’s deadliest animal? »
          The world’s deadliest animal is the sea wasp. It is a kind ...
Which are the different oils extracted from seeds? »
          The oil that we use in our kitchen or for the manufacture of ...
Why don’t leaves get heated in sunlight? »
            Anything exposed to the sunlight for some time ...
How do insects reproduce and develop? »
          Scientists have studied more than 800,000 species of ...
What are the different types of rhinoceros? »
The name ‘rhinoceros’ has Greek origin. In Greek rhino means ‘nose’ and keros means ...
Which is the most dangerous bird in the world? »
          The cassowary is the most dangerous bird in the world. Its ...
Why do woodpeckers peck the trees? »
               A woodpecker is a bird which ...
Which insects have the longest lifespan? »
               Most insects live only for a short span ...
Why does a peacock display its feathers? »
          A peacock displaying its feathers provides one of the most ...
Why do insects get attracted towards light? »
          You must have seen insects buzzing around a glowing lamp or ...
Which are the roots we eat? »
The roots of certain plants get swollen with stored food. They can be eaten as vegetables. The ...
Which plants feed on other plants? »
          Do you know that there are certain plants which cannot ...
Do insects have organs and blood? »
          Insect is such a tiny creature that it is difficult to ...
How do aquatic animals survive in frozen lakes? »
            In cold countries, when the temperature falls below ...
How do birds hear? »
               According to ornithologists, the ...
Does any animal wash its food? »
          Do you know any animal that washes its food before eating ...
Which sea animals emit light? »
               There are about 600 marine organisms ...
What are sulfa drugs? »
          Sulfa drugs are synthetic chemicals that are used to treat ...
Can a snake swallow an animal whole? »
          All snakes fall into the category of reptiles. Scientists ...
What were the dinosaurs? »
          For over 150 million years, the Earth was ruled by some of ...
What is a sea-horse? »
          The strange sea creatures, with large heads resembling the ...
How useful is the banana? »
          Banana is a popular fruit and an important part of our ...
How does an insect breathe? »
          Insects are found all over the world. They are small ...
Which animal never drinks water in its entire life? »
          All plants and animals need water for their survival. ...
What is a coral? »
           Man has been using the red corals in the jewellery ...
Can a squirrel really fly? »
          The squirrel is a familiar animal seen most everywhere. It ...
What are the magical qualities of garlic? »
          Man has been using garlic since ancient times to add ...
What is a flying fox? »
          The flying fox is not really a fox, but a large, ...
Do plants also breathe? »
          All living beings breathe in order to survive. In the ...
Why do some animals chew their cud? »
          Animals like cow, buffalo, sheep, goat and camel have the ...
Why do snakes shed their skins? »
          Snakes are long reptiles, having no legs. They probably ...
Does the vampire bat feed on blood? »
          Stories about vampires have been heard and talked about for ...
Why is a dog’s sense of smell better than that of ours? »
          Dog has been a faithful friend of man for thousands of ...
Why do rabbits have large ears? »
          Rabbit is a small furry mammal with a short tail and large ...
Why do we hiccup? »
          Whenever somebody hiccups, it is often remarked that he ...
Why do we get tired? »
          After a day’s work, we all get tired. Similarly we get ...
What determines the sex of a child? »
          When we look at the human race we find that it is divided in ...
How are we able to speak? »
          Of all the living beings only man can express himself in ...
How do the ears detect sound? »
          It is a well-known fact that different kinds of sounds ...
How do female mammals produce milk? »
               Apart from human beings, cow, buffalo, ...
Why is the blood red? »
          Generally a normal person has 4 to 5 litres of blood in ...
Why do tears come out while weeping? »
          Whenever somebody weeps, tears come out from eyes. Do ...
What makes people sneeze? »
          There are many stories and superstitions connected with ...
How is urine formed in our body? »
          We have two bean-shaped glandular organs in the lumbar ...
Why do some people snore during sleep? »
          It is often seen that some people snore during sleep. Their ...
How do we breathe? »
          Breathing is essential for all living beings. Men, ...
Why does the human skin have different colours? »
          All over the world people of different races have skin of ...
What is roundworm infestation? »
          Roundworms or Nematodes as they are named are among the ...
Why does the blood group vary from person to person? »
          Even though the blood of all the human beings looks ...
Why do some people become deaf? »
          Impairment of hearing is generally called deafness. It is ...
Why do we feel thirsty? »
          Most of the people think that parching of mouth or ...
What is pulmonary tuberculosis? »
          Pulmonary tuberculosis is an extremely infectious and ...
How are twins born? »
          Normally a woman delivers only one child at a time. This ...
How do we digest food? »
          The human body requires a constant supply of food in order ...
How does the nose detect smell? »
          The nose is an organ used for smelling and breathing. If ...
What causes headaches? »
          All of us get headache at one time or the other. ...
Why is cutting of nails and hairs painless? »
          Whenever some part of our body is hurt or cut, we experience ...
What are the common eye disorders? »
          Of all the five senses, sight is the most precious and ...
Why does our body stop growing after a certain age? »
          The process of growing up is a natural way of life. Plants, ...
What causes pneumonia? »
          Pneumonia is a disorder of one or both the lungs usually ...
Why are some people left-handed? »
          Most of the people in the world do most of their work ...
How do muscles work? »
          There are 639 muscles in our body. The shape and ...
How do fish breathe inside water? »
               We see many kinds of fishes in ponds, ...
How are bats different from birds? »
           According to the available fossil records, bats ...
How does a wall lizard get rid of its tail? »
            When a wall lizard is attacked by an enemy it often ...
How does a firefly glow at night? »
          The glowing fireflies or glow worms at night present a ...
Which are the warm and cold-blooded creatures? »
               On the basis of body temperatures, all ...
Can animals identify different colours? »
          We know that animals can see things like us. But can they ...
Why lion is called the king of the beasts? »
          Lion is the largest and most powerful of the wild cats. ...
Why is the colour of leaves green? »
          The new leaves of any plant appear pink but after some ...
Why insect bites are dangerous? »
          Amongst the thousand kinds of insects, there are some who ...
What are mammals? »
          Mammals are vertebrates or animals with back bones. They ...
Why don’t spiders get caught in their own webs? »
          The web made by a spider is a fascinating thing, but spider ...
Why do trees shed their leaves? »
          Most of the trees and plants shed their leaves during autumn ...
Why do camels have humps? »
          Camel is called the ‘ship of the desert’ because it has ...
Why do flowers have fragrance? »
          Whenever we pass through a garden during the spring the ...
How do we estimate the age of a tree? »
          On the basis of age, plants are divided into three ...
Why are some fruits sweet while others are sour? »
          Some fruits like watermelon, guavas, grapes, apples, ...
Why do elephants have trunks? »
          Elephant is the largest land animal of the present day. It ...
How do bees make honey? »
          Like us the bees also have colonies. No other class of ...
How fast can animals run? »
A few years ago, the American scientist and explorer Roy Chapman Andrews came to India as the ...
Which medicines are obtained from animals? »
          Scientists have already studied more than 8 million kinds of ...
How does a chameleon change its colour? »
          Chameleon is a variety of lizard which often changes its ...
What is the difference between fruits and vegetables? »
          Generally the edible-fleshy part with seeds which ...
How did life begin on earth? »
          Today we see innumerable varieties of insects, birds and ...
How do parrot and myna speak like us? »
          For centuries, man has loved the birds like parrot and myna. ...
Why do we perspire? »
          Our body is like a furnace. The food we eat acts like fuel ...
Why do we resemble our parents? »
          A cat produces a cat and a rat, a rat only. The neem tree ...
Why do women have a sweet voice? »
          Generally the voice of women is sweeter than men. Even boys ...
Does a black cat bring bad luck? »
          Many people all over the world regard the sight of a black ...
What are pain relievers? »
          A pain reliever is a drug that reduces pain without causing ...
Why do giraffes have a long neck? »
               Giraffe is the tallest land animal ...
What is a flying fish? »
          There is a kind of fish which can glide like a glider. ...
How fast can marine animals swim? »
          The sea abounds with different kinds of living creatures ...
Which animals resemble man? »
          Gorilla, chimpanzee and orangutan are some of the animals ...
Do some plants eat insects? »
               You will be surprised to know that there ...
What is a Dragon? »
         Dragon is a legendary dreadful monster that never existed in ...
What is Darwin’s theory of evolution? »
          For a long time it was believed that each form of life ...
How long can man survive without food? »
          Like air and water, food is also essential for all ...
Why don’t women have beard?»
            All mammals have some hair on their bodies and ...
How does our tongue tell us the taste?»
            Man has five senses of perception – skin, ...
What happens to our body in sleep?»
            Sleep is a bodily need that takes up about ...
What causes people to faint? »
               We often see that people faint on ...
Why are people dwarf? »
           Generally most of the people are of normal height, ...
How do we remember things? »
          Memory can be defined as the capacity to keep ...
Why does man grow old? »
          Every man in this world wishes to live long and nobody ...
What causes baldness in people? »
           There are many theories regarding baldness. Some ...
Why are vitamins essential for us? »
Just as carbohydrates, proteins, fats, inorganic salts and water are the essential parts of our ...
Why do we get fever? »
          The normal body temperature of a healthy man is 98.4°F ...
How do bones mend? »
A fracture is a break in a bone. Bones may break or fracture in several different ways. A ...
How does a wound heal? »
             When your skin gets a cut, the broken blood ...
Which of the body parts can be replaced with artificial parts? »
             During the past two decades bio-engineers ...
Why can’t animals talk like us? »
            In many stories it is told that animals can talk like ...
How is bark formed? »
              Bark is the protective outer covering of ...
How do plants take and make their food? »
            It is a well-known fact that trees and plants are ...
How do migratory birds find their way? »
Every spring millions of birds migrate from their winter quarters to the temperate regions ...
How do animals and pants survive in deserts? »
            Due to the scarcity of water and particular climatic ...
How do some creatures make a shell on their body? »
             You must have heard the sound of conch ...
Is Bamboo a tree or grass? »
             Majority of people believe bamboo to be a kind ...
What is regeneration? »
Would it not be wonderful if people who lost an arm or a leg or even a finger in an accident ...
What are bacteria? »
               Bacteria belong to the lowest category ...
What is Fungus? »
              ...
What is a Virus? »
                Viruses are micro organisms which ...
How far can a Kangaroo jump? »
              Kangaroos are marsupials (animals with ...
Why do the eyes of some animals shine in the dark? »
           Have you ever seen a cat sitting in the dark? Though ...
Why does the dog go mad? »
Dog is regarded as a faithful animal. But when it goes mad it becomes very dangerous. If a ...
Do Ants also have their kingdoms? »
            Ants are insects that belong to the order ...
How can an Owl see clearly at night? »
           An owl is a bird of prey with large head and eyes, ...
What are antibiotics? »
                Antibiotics are special kind of ...
What are salt meadows? »
Salt meadows are area at the sea coast that are not flooded daily by sea water like the ...
What is Scuba?»
Scuba is an acronym for Self-Contained Underwater Breathing Apparatus. It consists of a ...
What is Sleep debt?»
Sleep debt is a term used to describe the physiological phenomenon by which a person who has ...
What is Test tube baby?»
Test tube baby is a term commonly used for babies born after being conceived outside the body. ...
What is transgenic organism?»
A transgenic organism is a plant or an animal whose cells contain, besides their own genes, ...
What is Ultrasound?»
Any sound of frequencies above the limit of human hearing, that is, 20,000 hertz or more, is ...
What are Vaccines?»
Vaccines are preventive medicines which when introduced into the body protect it from a ...
What is Pacemaker?»
The pacemaker is a battery operated electronic device which transmits electrical impulses to ...
What is Nitrogen fixation?»
Nitrogen is essential for plants and animal life as it is a constituent of major bimolecules ...
What is Mutation?»
A change in the structure of a gene resulting in an altered gene product, that is a ...
What is Jet lag?»
A state of exhaustion experienced by air travellers when they cross several time zones in a ...
What is Hydroponics?»
Hydroponics is the commercial method of growing plants without using soil, by seeding them on ...
What is Human genome?»
Human genome refers to the entire genetic make-up of humans. The genes giving rise to specific ...
What is Quicksand?»
Quicksand is a bed of loose sand mixed with water. It is found in places such as river banks ...
What is Heatstroke?»
Heatstroke is a condition when the heat regulating mechanism of the body breaks-down. ...
What is Heart attack? »
A heart attack can be defined as a sudden stoppage of blood supply to any part of the heart ...
What is Genetic engineering?»
Genetic engineering is a technique of manipulating the DNA in cells to endow an organism with ...
What is Gene therapy?»
Gene therapy is a new and as yet largely experimental branch of medicine that incorporates ...
What is Cholesterol?»
Cholesterol is a complex fatty substance that is essential for the normal functioning of the ...
What is CAT scan? »
Cat scan (Computerized Axial Tomography), sometimes also referred as CT scan, is a technique of ...
What is Cancer? »
            Cancer is the ...
What is By-pass surgery?»
By-pass surgery is a technique of treating patients with blocked coronary arteries which ...
What is Biopsy?»
Biopsy is a simplified procedure of obtaining tissues from affected part(s), usually some ...
What is Biodiversity?»
The sum total of all living plants, animals and microbes is what is called biodiversity. The ...
What is Biodegradation?»
This is the process by which living organisms breakdown matter into its simpler ...
What is Acupuncture?»
Acupuncture is an ancient healing art practiced by the Chinese for several thousand years. The ...
What is Dialysis?»
Dialysis is a process of separating dissolved substances from a solution using a semi-permeable ...
What is DTP?»
DTP or Desk-top Publishing is a method of designing, editing and laying out a publication ...
What is Endoscopy?»
Endoscopy is a harmless and painless method of diagnosing diseases of any of the hollow organs ...
What is Biological clock? »
The biological clock is an in-built timing system found in all living organisms. It times the ...
What is Amniocentesis? »
It is a diagnostic technique to check for genetic abnormalities in unborn babies. The test ...
What is Allergy?»
Allergy is a state of hypersensitivity acquired through the exposure to a particular substance, ...
What is AIDS?»
Acquired Immune Deficiency Syndrome (AIDS) is the most devastating and fatal disease of the ...
How do Naphthalene balls keep away moths? »
The naphthalene balls used for keeping away harmful insects from damaging clothes are ...
How do Woollens keep us warm? »
Wool fibres are made of a particular protein (Keratin) which is a bad conductor of heat and as ...
How is Hail formed? »
Hail is formed in thunder clouds when ice pellets formed near the freezing level in the ...
How do Plants absorb nutrients from soil? »
Plants have special structures called root hairs for absorbing water and other nutrients from ...
How are Annular rings in plants formed? »
The annular rings or the alternating dark light circles seen in a cross section of a tree ...
How does Water rise in tall trees? »
Cells in the root hairs of plants contain dissolved sugars and salts. Water surrounding the ...
How is Expiry date of drugs determined? »
Most medicines, which are chemical compounds and their combinations, degrade with time. This ...
How do Herbicides kill weeds? »
Herbicides are chemicals used to destroy weeds without harming the useful crops. This is ...
How do Seeds sprout? »
Seeds sprout when favourable temperature (15.38°C), enough oxygen and moisture are available. ...
How do Fishes survive in frozen lakes? »
Lakes which appear frozen from the top never freeze completely. Only the top layer freezes and ...
How do Animals see at night? »
No animal can see in total darkness. However, some animals are capable of making use of faint ...
How do Lizards walk on walls? »
The feet of lizards are adapted for walking on rough as well as smooth surfaces. The lizards ...
How do Spiders spin webs? »
Spiders spin webs as a means of trapping insects. They have special organs called ...
How do Bees communicate? »
Besides chemicals called pheromones, bees use a kind of dance language to tell other bees in a ...
How do Bees make honey? »
Honeybees suck nectar from a wide variety of flowers. But each bee usually keeps to a ...
How do Camels survive in deserts? »
Camels can survive for days in deserts with little food and no water due to their unique ...
How do Fish generate electricity? »
Electricity in fish is generated by the normal functions of nerves and muscles together with a ...
How do Bats fly in the dark? »
Bats navigate by making use of sounds that they emit. The way these sounds bounce off from ...
How do Chameleons change colour? »
It is not quite correct to say that a chameleon can change its colour to match coloured ...
How do Dogs track culprits? »
All dogs have keenly developed senses of smell and hearing. Dogs naturally depend on their ...
How do Animals identify their off springs? »
Many methods, not all fail-safe seem to be used by the animals in identifying their young. ...
How is Artificial insemination done? »
Artificial insemination is a method used in animal husbandry to genetically upgrade stock by ...
How is IQ measured? »
IQ, or intelligence quotient, is commonly used as a measure of an individual’s level of ...
How does Sunlight produce vitamin D? »
Vitamin D is a group of about 10 fat soluble compounds. The form of vitamin D produced in ...
How is AIDS detected? »
AIDS is caused by a virus called Human Immunodeficiency Virus or HIV. The presence of this ...
How is Blood sugar measured? »
Sugars in our diet are converted into the glucose due to metabolism and which then goes into ...
How do Balms relieve pain? »
Pain is felt when the message reaches the brain via the nerves and the spinal cord. The ...
How do Fireworks display colours? »
The brilliant white, sparkling yellow, glowing red and the shimmering blue colours in the ...
Why don’t identical twins have identical fingerprints? »
Fingerprint formation is like the growth of capillaries and blood vessels in angiogenesis. ...
How do turtles reproduce?»
The turtle lives ‘twixt’ plated decks Which practically conceal its sex? I think it’s ...
How do spiders manage without getting caught in their own web?»
A thin coating of oil on the surface of the spider's legs prevents them from sticking to ...
Why is the sting of a scorpion more painful than that of a snake sting? What are the chemicals in their poisons?»
Scorpion’s venom acts on the nerve tips and roots whereas snake’s poison acts on dendrites ...
Can snakes hear? How do they respond to charmers’ mahudi?»
Snakes are stone deaf, yet they respond to charmers’ mahudi. Though this appears a ...
How do penguins survive and breed regularly in Antarctica despite the chill? »
The subject is being studied by Dr. Julian Vincent of Reading University’s Biomimetics ...
Why do we get a bulge on the skin after a mosquito bite? »
Stings of insect group animals like mosquito cause skin lesions by direct effects of the ...
When killed, some mosquitoes bleed and some do not. Why?»
 There are more than 1,200 species of mosquitoes but all of them do not feed on the ...
How do the large marine mammals manage to sleep without drowning? »
Some sleep out of the water, and some may not sleep at all. The furred or hairy aquatic mammals ...
How do leeches suck our blood without causing any pain?»
            Leeches, carnivorous or bloodsucking worms, live ...
How do leeches manage to prevent blood from clotting?»
  Clotting is a remarkable property of blood. Certain substances promote coagulation ...
Why the population of house files does suddenly increases in summer?»
The breeding season of house fly, Musca nebulo, is from March to October in most of India. ...
How does a firefly emit light?»
    Firefly also known as lightning bug is the common name for about 100 species ...
Why does hair fall?»
            Many factors are involved in hair loss. The ...
Why do we blink our eyes? »
 The object of blinking of our eyelids is to keep the front of the eyeball clean. ...
How do parrot’s talk?»
    Parrot’s vocal expressions are a result of imitation, not a part of its ...
With its small body mass, how does a monarch butterfly obtain enough energy to migrate 1,800 miles? »
                  ...
Why do snakes move in a zigzag manner? »
The snakes are the only vertebrates which have efficiently overcome the handicap of absence ...
Why does the light of firefly twinkle while that of glow-worm remains constant?»
            Fireflies are not really flies and glow ...
How do ants go in a line?»
     Ants are social insects. Many ant species go out of their nests in groups ...
How do ants manage to float on water?»
            Ants manage to float on water due to an ...
Ants do not get hurt when they fall. Why? »
            The fall of a body is controlled mainly by ...
How do ants find their way to hidden sweets?»
            Antennae, the two hair-like structures on ...
Why do birds never fall off their perches when sleeping? Do they, in fact, sleep? »
                    ...
Why do the eyes of some animals glow in the dark? »
The truth is that the glow is only the reflection of light from some other source. The ...
How do honey bees find their way back to their hives?»
            Bees live in colonies called hives. Each ...
Why don’t we have hair on our palms?»
      In humans hair is present in the skin of nearly every part of the body ...
What is the difference between hair and fur?»
  The difference between mammalian hair and fur is chiefly one of arrangement, not ...
Why are some insects attracted towards light?»
                  ...
How do insects enter and live inside mangoes?»
Adult females (about 6 mm long) of the mango nut weevil Sternochetus mangiferae Fabr puncture ...
Eagles do not flap their wings often, yet fly for long. How? »
            Eagles adopt an energy-saving flight mode ...
Why do our arms move to and fro when we walk? »
To keep our torsos stable and conserve energy, we swing our arms backwards and forwards ...
How do birds navigate home after long journeys? »
                  ...
Do sheep swim? If so, how do they learn?»
            Yes, sheep do swim, ...
It is true that a red flag agitates a bull? »
    It is generally believed that anything red makes a bull angry and causes it to ...
How come zoo animals like lions seem to lie around all day and yet stay fit? Also pet cats seem to lie around all day and yet stay fit?»
It is a partly a matter of appearances, with zoo animals less active at peak visiting ...
Why and how do falling cats land on their four legs, always? »
              ...
What imparts fragrance to flowers, fruits and species? »
            Fragrance in flowers, fruits and spices is ...
Fruits were supposed to attract animals. So what is the point of lemons tasting, so sour? Are there any animals which actually like the taste? Did we breed lemons from ones that were sweeter? Or do an»
            Plants use many methods to distribute ...
How do trees reduce air pollution?»
            Plants can prevent pollution of ...
Why do vegetables such as cucumber, snake gourd and bottle gourd sometimes taste bitter? »
   Bitterness is cucumber and other cucurbitaceae vegetable is due to the ...
Beetroot contains a red colour pigment called betacyanin. Does it aid in the formation of blood cells in any way? »
            Betacyanin is a group ...
Normally the bark of trees turn brown but in some the stem remains green even after a few years. Why? »
     In plants which show secondary growth the outer appearance of the stem ...
Why do some trees hold onto their leaves longer than others? »
            The timing of leaf loss varies with ...
Why are some portions of sugarcane red?»
    The red portion in the stem of cane is due to a fungal disease called red-rot ...
Why does the touch-me-not plant shrink when touched? »
                  ...
Why are leaves of crotons coloured? »
  Crotons are ornamental plants grown for their variegated leaves. The different coloured ...
What makes Venus fly-trap plant insectivorous? »
            Venus fly-trap, an insectivorous plant, ...
What is plant tissue culture?»
           Plant tissue culture (PTC) is the art and science ...
How do plants survive during certain season’s inspite of shedding leaves? »
Abscission is a physiological process whereby plants shed a part, such as leaf, flower or ...
How can we identify poisonous and non-poisonous mushroom? »
                  ...
Why do raw fruits such as mango ripen faster when kept in rice tins? »
   Ripening may be regarded as a special case of sequence. During ripening, a number ...
How does temperature affect ripening bananas? »
"Temperature changes can delay or hasten the ripening of banana. Banana is a tropical fruit, ...
How do fruits ripen? »
               Ripening of fruits ...
Why does apple turn brown on being cut? »
     Apple contains an enzyme known as polyphenol oxidase (it is a copper ...
Why do drops of lemon create white spots on the floor? »
                  ...
Why does the lotus leaf not get wet? »
            Lotus leaf does not get wet due to our ...
Why do flowers have different colours? »
The flavonoids are fifteen-carbon compounds that are generally distributed throughout the ...
Why does jasmine bloom only in the night? »
Nastic movement is responsible for blossoming of flowers. Usually this movement takes place ...
Why and how does the sunflower always face the Sun? »
Certain flowers such as sunflower are attracted to the sun strongly. They begin the day facing ...
Why does the Kurinji flower only once in 12 years?»
Before flowering, a plant must attain the ripe-to-flower condition. To attain this condition ...
What is terminator gene technology? How is it used to help our farmers? »
                ...
Why does the surface of boiling milk rise? »
            Milk is a fine suspension of fat and protein ...
Why does food feel tasteless when we have a cold? »
            There is a close link between the sense of ...
Why does food get spoiled? »
            Spoilage of foodstuffs is caused by ...
Why do plants flower? »
  Flowering is a natural mechanism by which the majority of plants perpetuate their ...
Why do plants need soil? »
            Like any living organism, plants need, ...
Why do the leaves of ‘Touch-me-not’ plant fold when touched? »
            All plants respond to touch, but Mimosa ...
ARE EMOTIONS REFLECTED THROUGH BODY LANGUAGE»
When your mother frowns at you without saying a word, you know that you have displeased her. ...
DO ANIMALS UNDERSTAND BODY LANGUAGE»
Some species of animals are especially clever at detecting human body language, both ...
Why is there a scent after it rains on parched soil? »
            The peculiar smell is produced by the soil ...
Why do vultures fly at a great height? »
            Vultures are scavenger birds which feed on ...
Why do butterflies have powder on their wings? »
     The wings of butterflies and moths are covered with small ...
Why do roots go down and shoots go up? »
            The direction in which roots and shoots move ...
Why do birds sing? »
            Most birds produce sounds in their throats ...
Why do animal’s eyes glow in the dark? »
         In animals belonging to the cat family and other nocturnal ...
Why do camels have humps?»
            The camel’s hump is filled largely with fat, ...
Why don’t birds fall off their perches while sleeping?»
            Most of the birds that we see around us are ...
Why do bees buzz?»
            The buzzing sound made by the bees is due to ...
Why do snakes flick out their tongues?»
 Snakes are unable to sniff the air through their noses quickly enough to follow the ...
Why do bats hang upside down?»
 Bats are flying mammals. However, unlike birds which can fly and walk as well, bats have ...
Why do birds migrate? »
       In many parts of the world which experience extreme winter, food ...
MEANING OF HEAD SHAKE»
When someone asks you if you want something, you will usually shake your head up and ...
Why does a lizard break its tail? »
The breaking-off of the lizard’s tail is a defense mechanism which helps the lizard to run ...
Why do we need to sleep? »
Sleep is a normal activity of higher organisms. Every human being, on average, spends a third ...
Why do we feel breathless on high mountains? »
  At high altitudes, the atmospheric pressure is much less than in the plains. As a ...
Why do we yawn? »
            Yawning occurs without any effort. It is a ...
Why do we perspire? »
      Perspiration is a mechanism for keeping the body cool in a hot ...
Why does water cause our skin to wrinkle? »
    The skin forms an elastic protective cover on our body. It consists of ...
Why does skin come in different colours? »
 Skin colour is due to the dark pigment melanin which is produced by pigment cells in ...
Why does sun bathing tan? »
Tanning is a sort of natural protection mechanism provided by nature to the human skin. It ...
Why do we have two eyes? »
The two eyes working together enable us to perceive depth which is not possible to do ...
EYE CONTACT»
Of all the ways we communicate with people, eye contact is the most powerful. Eye contact can ...
Why do we get headache? »
There are many reasons for headaches. It is, however, believed that we feel the ache when pain ...
Why do we blink? »
            Blinking helps to keep the eye lubricated ...
Why do men become bald? »
Both, men and women may be affected equally by temporary hair loss due to stress, skin ...
Why is body temperature measured under the tongue? »
 Body temperature can be measured by placing the thermometer under the tongue, in the ...
Why do bruises appear blue? »
 When one is hit, the force of impact damages the capillaries or the small blood vessels ...
Why do veins appear blue? »
            The red pigment of blood – haemoglobin ...
Why do we feel thirsty? »
            About 60 per cent of our weight is water. ...
BODY LANGUAGE»
Have you noticed that when someone is nervous, he bites his nails or that a person looks down ...
Why is it easier to aim with one eye closed? »
    Normally when images of an object are formed on the retina of the two eyes, ...
Why does our mouth water on seeing spicy food? »
            Our mouth starts watering on seeing or ...
Why don’t our eyelashes grow long? »
         The hair growing on our bodies have different ...
Why does a wound on the tongue heal faster? »
  Wounds on the tongue heal fast because the tongue has a rich supply of blood vessels. ...
Why don’t cuts on our fingers affect our fingerprints? »
               Usually a person’s fingerprints do ...
What are the different types of handshakes?»
            When you meet another ...
Why don’t we feel pain when cutting hair/nails? »
            Pain is felt only when a nerve end is stimulated by ...
Why are transplanted organs rejected? »
 Transplanted organs are rejected because of the presence of special protein molecules ...
Why do baby teeth fall out?»
Baby teeth or milk teeth fall out to accommodate the full complement 32 teeth in the growing ...
Why doesn’t the stomach digest itself?»
            The stomach is a muscular bag-like organ that ...