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Electronics is the study of devices in which the movement of electrons is controlled, usually within a vacuum or semi-conducting material. An electron (Greek, electron ‘amber’) is the fundamental particle of electrical charge and gives rise to an electric current when the electrons are set in motion travelling through a material.
Electronics is one of the fastest growing areas of electrical science and engineering and has a tremendous impact on our everyday lives, from the television sets we watch at home to the computers we use at work. The formal discovery of the electron in 1897 by J.J. Thomson in Britain, and its classification as a charged particle, have led to greater understanding of all materials around us, by stimulating research which led to the formalization of quantum theory. Prior to Thomson\'s work, there was a general acceptance that a fundamental unit of electric charge existed, originating from work with electrolysis and cathode rays. Modern cathode ray tubes are used to provide the picture in television sets.
The first commercial electronic device was Edison\'s diode, or thermionic valve, discovered in 1880 through Edison\'s work with incandescent light bulbs. At the time, the electron had still not been ‘discovered’ and explained, though Edison later realized that this was what caused his diode to function. The light bulbs, which contained a filament of wire enclosed in a vacuum, were found to conduct electricity from the filament, through the vacuum, to another wire suspended in the vacuum and connected to the positive end of the filament. The ‘Edison effect’, as it became known, permitted current to flow in one direction only, from the filament to the wire, and was to find use in early radio receivers (see radio transmission).
The next major development in electronics was an extension of the diode, by Lee De Forest; it was called a triode as it had three pieces of wire in it. De Forest proved that a triode could be used as an amplifier, that is, it received weak radio signals, boosted them electronically and output a much stronger reproduction of the input signal. This greatly improved the quality of radio receivers.
The early electronic devices, although successful in their own right, were handicapped primarily by unreliability and fragile construction. With the advent of semiconductor devices, which in most cases had greatly improved reliability and performance, the electronics explosion of the post World War II period began. The first significant semiconductor electronic device was the transistor, or ‘transfer resistor’, which was developed, along with the theory of semiconductor devices, to be a semiconductor ‘copy’ of a triode. The transistor functioned as a very good amplifier and was, and still is, used in millions of radio sets.
As the manufacturing of semiconductor devices was improved and refined, miniaturization of transistors became possible and a new era of electronics began: microelectronics. Microelectronics has permitted the construction of electronic circuits having tens of thousands of transistors in pieces of semiconducting material no larger than a fingernail. Technology such as this has allowed previously obscure areas of engineering and science such as digital logic to be physically realized, and computers today all use microelectronic circuitry. AC |
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