Category Electricity

         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.