Semiconductors

JEE Main level, single correct, medium

120 of 209

Question 120 of 209

Which of the following statement is not correct in the case of light emitting diodes?
A. It is a heavily doped p-n junction.
B. It emits light only when it is forward biased.
C. It emits light only when it is reverse biased.
D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used.
Choose the correct answer from the options given below :

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Answer: (C) C

The structure of the LED has a high level of doping so that it can work on the principle of the interconversion of the light and electricity. It is in forward biased so that it can emit light spontaneously when connected as it reduces the efficiency of energy barrier. It will not emit light in reverse biased condition.
The energy of radiation emitted by LED is not greater than the band gap of the semiconductor used.

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