My Science School

Har Gobind Khorana (9 January 1922 – 9 November 2011), was an Indian-American biochemist who shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that showed how the order of nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins. Khorana and Nirenberg were also awarded the Louisa Gross Horwitz Prize from Columbia University in the same year.

Khorana was born in Raipur, British India (today Tehsil Kabirwala, Punjab, Pakistan) and later moved to become an Indian citizen after the partition of 1947. 

Fields 

• Molecular biology

Institutions

• MIT (1970–2007)


• University of Wisconsin, Madison (1960–70)


• University of British Columbia (1952–60)


• University of Cambridge (1950–52)


• Swiss Federal Institute of Technology, Zurich (1948–49)

Notable awards

• Nobel Prize in Medicine (1968)


• Gairdner Foundation International Award (1980)


• Louisa Gross Horwitz Prize


• ForMemRS (1978)


• Albert Lasker Award for Basic Medical Research


• Padma Vibhushan


• Willard Gibbs Award

 To read more about Har Gobind Khorana  Click https://en.wikipedia.org/wiki/Har_Gobind_Khorana

Thales of Miletus is an important figure in the history of electricity. It is said that he discovered static electricity around 600 BC.

Static electricity was first observed when amber, rubbed with animal fur, got charged, and attracted light objects such as dry leaves, or bits of straw. Even though other people may have noticed this before, it was Thales who first recorded his findings. But Thales has never identified it as static electricity. At that time magnetism was also confused with static electricity.

Later, it was proved that the force that works between amber and animal fur is nothing but static electricity. Thales’ role was remarkable because he was the first to record his findings regarding static electricity. Thales was born in the city of Miletus around the mid 620 BC. He was a philosopher, and astronomer and the one who conducted the earliest studies in electricity. Thales’ findings were recorded but none of them survived to modern times. 

             Stephen Gray was an English astronomer who made significant contributions to science. These include his experiments with conduction, insulation, and electrostatic induction.

           One of his experiments was done using a glass tube. Gray observed that when the glass was rubbed with a dry hand or dry paper, it obtained electric charge. As a result, it attracted a feather to the glass, as well as the cork with which it was closed. The cork was in fact, used to keep the dust out when not in use.

          From the experiment, Gray concluded that the ‘attractive virtue’ passed from the tube to the cork.

         To clear his doubts, Gray proceeded with a similar experiment. This time, he attached an ivory ball to a piece of wood, and inserted the other end of the wood into the cork. Once it was done, he confirmed that attraction and repulsion passed to the ball, that too stronger than that on the cork.

         Gray observed that substances like silk do not conduct electricity. And that Earth was somehow responsible for conducting electric charge away from the body.

         For his electrical experiments, Stephen Gray received the first Copley Medal instituted by the Royal Society, in 1731. However most of his works went unacknowledged and he died as a poor man.

 

        Fuel cells are devices that generate electric current through chemical reactions. To put it better, a fuel cell uses chemical energy of hydrogen (or another fuel) to produce electricity in a clean and efficient manner. Its only products are electricity, heat, and water, and hence it is clean.

            There are a wide range of applications for which fuel cells can be used. This includes transportation, emergency power back up, material handling etc. compared to other technologies, fuel cells have many advantages. They are more efficient, and have lower emissions. That is, they do not emit dangerous substances like carbon dioxide or air pollutants, as their only products are water and heat. Yet another advantage is that fuel cells operate in a silent manner.

            The history of fuel cells began with the Welsh physicist Sir William Grove. In 1839, he demonstrated the first crude fuel cells. Although many people have tried to work on the concept of converting chemical energy into electric power, most of them were unsuccessful due to lack of resources.

            The first successful fuel cell was developed by the British engineer Francis Bacon in 1932, using hydrogen, oxygen, an alkaline electrolyte and nickel electrodes.

 

            A transformer is an electrical device that works on electromagnetic induction to transfer electrical energy between two or more circuits. It is used in a wide range of power appliances to increase, or decrease voltage.

            We see transformers in almost every city. They are used to convert high-voltage electricity from incoming power lines, to lower-voltages.

         

Continue reading "Why is it said that the invention of the transformer was a turning point?"

            To put it simply, a transistor is an electronic component that can do two different jobs. It can act as an amplifier or a switch, depending on the need.

            As an amplifier, a transistor does the job of boosting current. That is, it takes in a tiny input current at one end and produces a bigger output current at the other end.

            It was at the Bell Laboratories in New Jersey that transistor was demonstrated for the first time. That happened on December 23rd, 1947. William Shockley, John Bardeen and Walter Brattain are the three persons credited with its invention.

            In 1956, they were awarded the Nobel Prize in Physics “for their researches on semiconductors and their discovery of the transistor effect”.

         In one of his experiments, Thomas Alva Edison discovered that electrons can flow from one metal conductor to another, through a vacuum. This discovery was later named as the Edison Effect.

         Sometime in the early 1880s, Edison and his team were working to find a light bulb filament. Their carbonized bamboo filament did well, but even so, carbon deposits were seen inside the bulb after hours. That was when he noticed that the carbon came from the end of the filament which was attached to the power supply. It looked as though it was flying through a vacuum onto the walls!

          Edison realized that there was electric charge flowing not just through the filament, but through the evacuated bulb as well.

          Although Edison was right about the flow, he could not find the reason behind it. He moved on to other experiments.

           Later, it was proved that Edison, with his experiment, discovered the basis of the vacuum tube. And the modified light bulbs were later used to control the flow of electrons through vacuum. 

         Different kinds of electric lamps were invented by masters in the past.

         The English inventor Humphrey Davy’s electric arc lamp was one such creation that made great changes in the field of electricity and lighting.

         However, the arc lamps were not flawless. Their biggest disadvantage was that they were not fit for practical use. They emitted too much of light and also, burnt out quickly. Nevertheless, the principle of arc lamps was used till the 1900s by various inventors for developing electric lights and bulbs. Among them were Warren de la Rue and William Staite.

            In 1840, the British scientist Rue developed a light bulb using coiled platinum filament instead of copper. Staite, on the other hand, had been working on increasing the longevity of conventional arc lamps. In 1848, he developed a clockwork mechanism. Through this, he was able to regulate the movement of the carbon rods used in the lamps that eroded very quickly. 

        The story of the invention of the electric bulb was very interesting. Even though many believe that it is Thomas Alva Edison who discovered the light bulb, it was not so. He played a major role in the development of the light bulb, and its popularity. The story of the light bulb begins long before Edison patented the first commercially successful bulb in 1879.

          Alessandro Volta’s invention of the battery in 1800, gave inspiration to many scientists. One among them was Humphrey Davy. He produced the world’s first electric lamp by connecting voltaic piles to charcoal electrodes. It cannot be called an electric bulb as such. It was an electric arc lamp, and he introduced it in 1802. It was named so for the bright arc of light emitted between its two carbon rods. However, Davy’s arc lamp wasn’t a very practical source of lighting. It was much too bright for use in a home, and it burned quickly. But the principles behind this arc light were used throughout the 1800s, and many took inspiration from this invention.

          Another person who made significant contributions to the making of the electric bulb is Sir Joseph Wilson Swan.

          Swan was an English chemist. During the 1850s and 1860s, he conducted many experiments on bulbs using carbon filaments. Most of them failed, because the vacuum pumps used in those times were not good, so they couldn’t remove enough air from the lamps. Besides, the lamp deposited a dark layer of soot in its inner surface. This obscured the light.

          In 1878, Swan demonstrated an improved working lamp. It had a better vacuum, and carbonized thread as a filament. The method of processing was such that the bulb avoided early blackening. Soon after the demonstration, Swan was granted a UK patent. After that, light bulbs were installed in homes in England. In 1880, he received a US patent too.

              For his contributions, Swan was knighted in 1904. The same year he also received the prestigious Hughes Medal, instituted by the Royal Society of London. 

          We saw that during the 1800s, many inventors have worked hard to develop an effective light bulb. But, the most successful among these inventors was Thomas Alva Edison.

          Edison’s serious research into making a practical incandescent lamp began around 1878. He wanted to invent a safe, yet cheap electric light that could replace the earlier ones. Between 1878 and 1880, he conducted many experiments, with carbon filaments, platinum, and other metals. In 1879, he successfully tested a bulb with a carbon filament that lasted 13.5 hours.

          The following year, Edison and his team discovered that a carbonized bamboo filament could last over 1200 hours. This marked the beginning of commercially made light bulbs in 1880.

          As we know, this is just one of the many inventions made by Edison.

          Thus, Edison’s contributions remain unparalleled and, for his tireless work, he was rightfully described as one of the greatest inventors. 

Scientists and inventors have used a number of filaments for incandescent bulbs in the past. But today, the most popular one is the tungsten filament.

It was William David Coolidge, who developed a method to manufacture tungsten filaments in 1910.

The biggest advantage of tungsten was that it had a high melting point, and was able to withstand heat and corrosion. That is exactly what attracted inventors to it. Besides, using inert gases inside the bulb increased its luminescence.

As years passed, the element was used in other lamps too, including halogen, fluorescent, mercury vapour etc. Tungsten is perhaps the most durable type of filament used in bulbs even today.

It is said that Thomas Alva Edison himself knew that tungsten would prove to be the best choice for filaments. But in his day, the technology and machinery required to produce the wire in fine form was not available.

Georg Simon Ohm was German physicist who formulated the ‘Ohm’s Law’.

       It states that current flow through a conductor is directly proportional to the potential difference or voltage, and inversely proportional to the resistance. The law was important, because it marked a successful start to the analysis of electric circuits.

         In 1827, Ohm published his book titled ‘The Galvanic Circuit Investigated Mathematically’ in which the Ohm’s Law first appeared.

         Although it was later treated as an important work that influenced the theory and applications of electricity, the book did not receive enough acceptances when it was published. It is said that Ohm resigned his post as a teacher from Jesuit Gymnasium of Cologne due to this.

        A few years later, Ohm’s Law started getting noticed, and Ohm was appreciated. In 1841, the Royal Society of London awarded him its prestigious the Copley Medal considering his contribution.

        The physical unit measuring electrical resistance ‘ohm’ was named after him. 

       Maxwell’s equations refer to a set of four equations that describe the creation and propagation of electric and magnetic fields. They are named after the Scottish physicist James: Clerk Maxwell, who made significant contributions to unify the theories of electricity, magnetism, and light. The early form of these equations was published between 1861 and 1862, and it proposed that light is an electromagnetic phenomenon.

       The equations formed from these laws could give an explanation to many phenomena around. For instance, how hair stands on end when one removed a nylon sweater, how a compass needle points north all the time, how a power station turbine generates electricity etc. Together, they could also describe the transmission of radio waves, and the propagation of light.

       Hence, Maxwell’s equation, along with the Lorentz force law, is said to form the foundation of classical electromagnetism. Lorentz force law describes the force acting on a moving point charge ‘q’ in the presence of electromagnetic fields. 

Dr. Vasant Ranchhod Gowarikar (25 March 1933 – 2 January 2015) was an Indian scientist. He was the chief of Indian Space Research Organization and also the scientific advisor to the Prime Minister of India in 1991–1993.Gowarikar made valuable contributions to the fields of space research, weather and population. He was well known for his monsoon forecast model as he was the first scientist to develop an indigenous weather forecasting model that predicted the monsoon correctly.

Awards

• Gowarikar was awarded Padma Shri in 1984


• Padma Bhushan in 2008.


•  He also received the Fie Foundation Award.

Career

He had worked with the Indian Space Research Organization  Gowarikar was involved in space research in early career under Vikram Sarabhai when his office was in the building of the local St Mary Magdalene Church in Thumba in Kerala. He pioneered solid propellant development and later served as Director of the Vikram Sarabhai  Space Centre (VSSC) between 1979 and 1985.

Gowarikar also served as the scientific advisor to Prime Minister of India P.V. Narasimha Rao from 1991 to 1993. He had also been the Secretary of Department of Science and Technology.

He was appointed as Vice-Chancellor,Pune University and was chairman of the Marathi Vidnyan Parishad between 1994 and 2000. Gowarikar, along with his associates, also compiled The Fertilizer Encyclopedia (2008) that featured 4,500 entries detailing the chemical composition of fertilizers, and containing information on everything from their manufacturing and application to their economic and environmental considerations.

To read more about Vasant Gowarikar Click https://en.wikipedia.org/wiki/Vasant_Gowarikar