My Science School

Electricity in a wire creates the pushes and pulls that get work done. It lights lamps and runs machines. But electricity has another important use. It can carry information. Thanks to electricity’s ability to carry information, we have tiny radios, handheld calculators and video games, and personal computers.

The use of electricity to carry electric signals is called electronics. These electric signals may stand for sounds, pictures, numbers, letters, computer instructions, or other sorts of information.

An electronic device has many tiny electrical pathways called circuits. Each circuit has a special job. Some circuits store signals. Others change signals. For example, in an electronic calculator, one circuit might add two numbers together. When the answer is reached, another circuit sends a signal that light up a display screen to show the answer.

The circuits in most of today’s electronic devices are mounted on a chip, a piece of material that is no bigger than a fingernail.

Picture Credit : Google

Electricity can make light and heat. It can also make a magnet. But this is a magnet you can turn on and off.

A magnet made with electricity is called an electromagnet. An electromagnet has two parts. The first part is a solid centre, or core, made of iron. The second part is an outer covering made of wire that is coiled many times around and around the solid iron core.

When an electric current runs through the wound wire, the iron becomes a magnet. The iron gets its pull, or magnetism, from the moving electrons in the wire. As soon as the electric current is turned off, an electromagnet loses its magnetism.

Electromagnets are used to make electric motors run. A motor has two sets of these magnets - an outer set that stays in place and an inner set that moves. The inner set of electromagnets is attached to an axle - a rod that can spin. When the motor is turned on, the two sets of electromagnets push and pull against each other. That push makes the inner magnets move and spin the axle. And the spinning axle gives a push that makes the motor run.

Picture Credit : Google

A torch runs on electricity, but you don’t have to plug it in. It carries its own electric current in a “package” - a battery.

A battery is made of layers of chemicals inside a metal container. When the torch is turned on, some of the chemicals in the battery break apart and eat away at the metal container. As this happens, some of the metal atoms leave the container and combine with the chemicals inside the battery.

As the metal atoms move away from the container, they leave some of their electrons behind. So the container gains electrons. And as the chemicals inside the battery break apart, they lose electrons.

Soon, there are more electrons in the container than there are inside the battery. Then the extra electrons in the container begin to move out of the battery. They travel through the bulb and back into the middle of the battery, where electrons are scarce. The push of these electrons is the current that makes your torch shine.

It may sound as if everything happens very slowly, but, as you know, it all takes place in an instant.

Picture Credit : Google

You want your electric clock to run day and night. But you wouldn’t want your doorbell ringing all the time. Things like doorbells, lamps, and radios work only when you turn them on.

Most things that run by electricity have a switch. A switch is used to turn the electric current on and off. The electric current moves along the wire and across the switch to another wire inside the bell, lamp, or radio. The switch is a “bridge” in the path the electricity follows.

A metal piece inside the switch moves when you turn the switch on and off. When you turn the switch on, the metal piece touches both wires. The “bridge” is down. The electricity coming into the switch can cross the “bridge” and keep travelling along the pathway.

When you turn the switch off, the metal piece moves away from the wire. The “bridge” is up. Without the “bridge,” the electric current can’t cross the switch and follow the path. So, the electric current stops moving, and things stop working until you lower the “bridge” in the pathway by turning the switch on again.

An electric current is a push in a wire - the push of moving electrons. But what makes the electrons start to push through the wire? Where does the current come from?

The electric current is made in a kind of “electricity factory” called a power plant or power station. The special machine that makes electricity is called a generator.

A generator uses a huge, spinning magnet to make electrons move. The pull of the spinning magnet is strong enough to start electrons pushing in a wire.

The magnet is surrounded by a large coil of tightly wound wire. When the magnet begins to spin, its pull starts millions of electrons pushing! This push makes a strong electric current in the coiled wire. The current is sent through other wires from the power plant to your home.

A generator makes electrical energy. But a generator uses energy, too. Running water, burning fuel, or nuclear energy runs the engines or other machines that make the huge magnets spin. So a generator actually is an energy-changing machine. It changes other kinds of energy into electrical energy - energy you can use.

Picture Credit : Google

When you use electricity to iron your clothes or toast your bread, two things happen. Electricity makes a strong push in a wire, and the wire pushes back!

Electricity makes the iron and the toaster heat up. The electricity travels into and out of these machines on wire pathways. Most of the pathways conduct electricity easily, so the electrons are free to move.

But inside the iron and the toaster, part of the pathway is made of a different kind of wire. This wire is made from a kind of metal in which the electrons don’t move very easily. Often the wire is very thin, and sometimes it is wound into a long, tight coil. Instead of conducting electricity easily, this part of the pathway resists the current. The electrons have to push hard to move through this wire.

The pushing electrons make the molecules in the wire speed up and bump into one another. The harder they bump and push, the hotter the wire gets. In a few minutes, the bumping and pushing make the wire hot. And the heat presses clothes or toasts bread.

In irons and toasters, resistance is a good thing. But in many machines, resistance is a waste of electricity. So scientists are always working to create materials that can conduct electricity without resistance. These materials are called superconductors. Someday, people may travel on high-speed trains that float on superconducting magnets. Test models of these trains have already reached speeds of more than 400 kilometres per hour.

When you turn on a lamp, electricity makes the bulb light up. How?

The electricity flows through a wire into the bulb. It travels around a wire inside the bulb. Then it leaves the bulb. Part of the electricity’s path through the bulb is a filament, a very thin thread of coiled wire. The filament is so thin that electrons have to push hard to get through.

The push of the electrons makes the molecules in the filament move faster. As the molecules speed up, they get so hot that their electrons give off energy. Then the filament glows.

The filament in the light bulb is made of metal called tungsten. A tungsten wire can get very hot without burning or melting. But as tungsten is heated, its molecules very slowly change to a gas and leave the wire. So, as the light bulb glows, the filament gets thinner and thinner.

After many hours of use, the filament breaks. The bulb is “burned out”. The electricity can’t get across the break in the filament. Then you put in a new bulb. Now the electric current has a path to follow. The lamp lights up again.

Picture Credit : Google

Click! When you turn on a lamp, a light bulb glows. When you turn on a radio, sounds come out. But electricity doesn’t just jump into the lamp or the radio. It flows through wires.

The lamp and the radio run on an electric current. An electric current travels along a pathway made of wires.

The centre of the wire is made of metal, such as copper. Metals have electrons that are free to move. So the electrons can move along the metal. The outside of the wire is made of rubber or plastic. The electrons in rubber or plastic are held tightly to their atoms. They can’t move from one atom to another.

When the electric current is turned on, the metal part of the wire conducts, or carries, the electricity. The electrons push along the wire from atom to atom, conducting electrical energy. But the plastic or rubber covering doesn’t conduct electricity. It insulates, or seals off, the wire. It keeps the electrons moving along the wire to your lamp or radio and back again.

Have you ever felt sparks fly when you pulled your jacket off? Or did you ever get a crackling shock when you touched a doorknob? These things happen because your body has been collecting electricity.

The sparks and crackles are called static electricity - electrons that pile up in one place. On cool, dry days, you scrape electrons loose from things. When you walk across a rug, or when your jacket rubs against you, the loose electrons stick to your body.

The loose electrons cannot flow through you. But they can jump from you to a material that has fewer electrons. So when you touch a doorknob or pull off your jacket, that’s exactly what happens. Then you hear the crackle of jumping electrons - and sometimes you feel it, too!

See the pull that electrons make by creating your own sticky balloon. Blow up a balloon and tie a piece of string to it. Rub the balloon with a wool cloth. Then touch the balloon to the cloth and let go of the string. When you rub the balloon with the cloth, it picks up electrons from the cloth. The balloon then has more electrons than the cloth. When you put the balloon next to the cloth, the piled-up electrons on the balloon begin to move back to the cloth. They pull so hard that the balloon sticks to the cloth. That’s static electricity!

Picture Credit : Google

When you turn on a light, ring a doorbell, or plug in a toaster, you start a parade. But it’s a parade you can’t see! It’s a parade of moving bits of energy that are called electrons. Inside every electric wire, there are many millions of electrons. When you press a button or turn a switch, they move through the wire. They make a strong push that gets work done. The energy of the moving electrons is called electricity. It makes the light, the doorbell, and the toaster work.

Electricity is the flow of tiny particles called electrons and protons. It can also mean the energy you get when electrons flow from place to place. Electricity can be seen in nature in a bolt of lightning. Lightning is nothing but a large number of electrons flowing through air all at once, releasing a huge amount of energy. Scientists have also learned how to generate, or create, electricity. This is useful because electricity that is generated can be controlled and sent through wires. It can then power such things as heaters, light bulbs, and computers. Today, electricity provides most of the energy to run the modern world.

Picture Credit : Google