Which one 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:
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:
- A.A
- B.B
- C.C and D
- D.C
Show answer and solution
Correct option: D
Solution
An LED emits light when forward biased (not reverse biased), as forward bias causes electrons and holes to recombine at the junction, releasing energy as photons. Statement C claims it emits light only when reverse biased, which is completely wrong. Statement D is correct — the photon energy emitted equals or is slightly less than the band gap energy of the semiconductor. Therefore, only statement C is incorrect.
[JEE Main 2023 · 29 Jan · Shift 1]