Question

Which of the following statements is not correct in the case of light emitting diodes (LEDs)?
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 then the energy gap of the semiconductor used.
Choose the correct answer from the options given below:

• A. C and D
• B. C
• C. B
• D. A

Hint:

For LED behavior:
• LEDs work only in forward bias.
• The emitted photon energy corresponds to the semiconductor’s bandgap.

Answer 1

The Correct Option is B

1. Correct Statements:
   • A: Correct. LEDs are made from heavily doped p-n junctions.
   • B: Correct. LEDs emit light only in forward bias.
   • D: Correct. The emitted light energy corresponds to the bandgap.
2. Incorrect Statement:
   • C: Incorrect. LEDs do not emit light in reverse bias.

Answer 2

⇒ LED is a heavily doped, forward biased p-n-junction diode
⇒ It will not emit light in reverse bias 
⇒ Energy of emitted photon is equal to or slightly less the band gap energy of forbidden band