Question

Photodiode is a device

• A. in which photocurrent is dependent on reverse bias.
• B. in which photocurrent is independent of incident radiation.
• C. which is always operated in forward bias.
• D. which is always operated in reverse bias.

Hint:

It detects light in reverse bias.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
A photodiode is a p-n junction diode that converts light into current. When light falls on the depletion region, it creates electron-hole pairs.

Step 2: Operating condition:
It works in reverse bias. In reverse bias, the dark current is very small, so the extra current caused by light is easy to notice. In forward bias, the large forward current would hide it.

Step 3: Check the options:
(A) The photocurrent depends on the intensity of light, and is nearly independent of the reverse bias value. (B) The photocurrent depends on the incident radiation. (C) It is not operated in forward bias. (D) It is always operated in reverse bias, which is correct.

Final Answer:
A photodiode is operated in reverse bias. \[ \boxed{D:\ \text{always operated in reverse bias}} \]