Question

Select the wrong statement in the case of LED.

• A. It emits light only when it is reversed biased.
• B. It emits light only when it is forward biased.
• C. The energy of light emitted is equal to or slightly less than the energy gap of the semi-conductor used.
• D. It is a heavily doped p-n junction.

Hint:

An LED is a p-n junction that emits light only when it conducts, which happens in forward bias.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
A light emitting diode (LED) is a heavily doped p-n junction that works in forward bias.

Step 2: Check each statement
(A) Says the LED emits light only in reverse bias. In reverse bias there is no recombination current, so this is wrong.
(B) Forward bias gives recombination of electrons and holes and light emission, so it is correct.

Step 3: Remaining statements
(C) The emitted photon energy is equal to or slightly less than the band gap, which is correct.
(D) An LED is a heavily doped p-n junction, which is correct.

Step 4: Compare the options
The wrong statement is option (A).

Final Answer:
The wrong statement is that an LED emits light only when reverse biased. \[ \boxed{\text{(A) }\text{It emits light only when it is reversed biased.}} \]