129. L. E. D.

A light emitting diode (LED) is a semi conductor light source. When a semi conductor diode is switched on, it can release energy in the form of photons. This effect is named as Electroluminescence.

This effect was first discovered in 1907, by H.J.Round of Marconi Labs. No practical use was made of this discovery for several decades.

The first practical visible spectrum of LED was developed in 1962, by Nick Holonyak Jr, rightfully called “The father of LED”. In 1962, LED was introduced as a practical electronic component. Early LED emitted very low intensity light.

Until 1968, LED was extremely costly and had very little use. The first commercial LED was a replacement for incandescent and neon lamps. Later LED was used in T.V, radio, telephone, calculator and watches.

Very bright modern versions of LED are available now, in the visible, infrared as well as ultraviolet wave lengths. Today LED is used for aviation lighting, automobile lighting, in indicators and traffic signal lights.

The compact size of the LED has made it possible to develop new text and video displays and sensors. The faster switching frequency is useful in advanced communication technology. Infra red LED is used in the remote control units of the T.Vs, DVD players and other domestic appliances.

Visalakshi Ramani


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