9781422276006

Electron All forms of matter present around us are made up of atoms. An atom is the smallest indivisible part of matter. An atom is made up of a central core, called a nucleus, and a few charged particles. The positively charged particles are called protons. The negatively charged particles are called electrons, and the neutral particles are knownas neutrons. These particles may remain attached to the central core or move around freely. The freely moving electrons passing through an object or through a medi- um generate an electric current.

Early history In 1883, Thomas Alva Edison stud- ied and explained that electrons can move from one metal conductor to another through a vacuum. This effect is known as the Edison effect and led to the development of the vacuum tube. However, the exact principle was only understood after the discovery of the electron by J. J. Thompson in 1897. After the vac- uum tube, the diode was invented in 1904. This development further paved way for the invention of the triode. These devices were ideal for transmitting and amplifying electri- cal signals. They were first used for radio communications in 1901. Soon these electronic components were used in television from the 1920s to the 1950s. However, they proved inef- ficient foruse incomputers. Therefore, a new electronic component called the transistor was invented. It was much better than the earlier devices. It was only after the 1950s that the use of semiconductor devices and integrated chips came into use.

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SCIENCE FACTS

● ● The mass of a single neutron or proton is one thousand eight hundred times greater than the mass of an electron. ● ● The number one electronic device in most homes, in terms of energy use, is the television.

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ELECTRONICS