What does LED stand for?

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IPRC ISRO Technical Assistant Electronics 21 April 2018 Official Paper
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  1. Light Emitting Display
  2. Low Energy Display
  3. Light Emitting Diode
  4. Light Emitting Detector

Answer (Detailed Solution Below)

Option 3 : Light Emitting Diode
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Detailed Solution

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LED stands for Light Emitting Diode.

LED (light-emitting diode):

  • The LED (light-emitting diode) is a PN junction device that emits light when a current pass through it in the forward direction, i.e. when LED is forward biased, it emits light.
  • In an LED, this energy lies in the visible region of electromagnetic radiation, and the photon released is perceived as light.

  • An LED in this way converts electrical energy into light energy.

    F1 R.D. N.J 05.09.2019 D 5

  • In reverse biased mode, it works like a normal diode and does not emit light.
  • It is an optical semiconductor device that emits light when voltage is applied means it converts electrical energy into light energy.
  • When Light Emitting Diode (LED) is forward biased, the free electrons from the n-side and the holes from the p-side are pushed towards the junction.
  • Light-emitting diodes emit either visible light or invisible infrared light when forward biased.
  • The LEDs which emit invisible infrared light are used for remote controls.
  • LEDs that can emit red, yellow, orange, green, and blue light are available for commercial use. 
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