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Question 20224
JEE Physics · Easy

Semiconductors: LED MCQ

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LEDEasyQuestion 20224

Question

LED emits light when:
  1. A
    Reverse biased
  2. B
    Forward biased — electron-hole recombination releases energy as photons
    Correct
  3. C
    At zero bias
  4. D
    Heated

Correct answer

Forward biased — electron-hole recombination releases energy as photons

Explanation

In forward-biased LEDs, electrons from n-side and holes from p-side recombine at the junction. The energy released = Eg (band gap) is emitted as a photon: E = hf = Eg. Colour of light depends on the semiconductor material (GaAs: IR; GaAsP: red; GaN: blue).

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