NEET Physics: Semiconductors questions with solutions

Q1. Photodiode is a device

1. Which is always operated in reverse bias
2. Which is always operated in forward bias
3. In which photo current is independent of intensity of incident radiation
4. Which may be operated in forward or reverse bias

Answer: Which is always operated in reverse bias

A photodiode is designed to operate in reverse bias so that incident light creates electron-hole pairs in the depletion region, producing a measurable photocurrent. Reverse bias improves sensitivity and response speed, while forward bias is not the normal operating mode.

Q2. In which of the following doped semiconductors majority of charge carriers are holes?

1. Antimony doped with germanium
2. Boron doped with silicon
3. Arsenic doped with silicon
4. Phosphorus doped with germanium

Answer: Boron doped with silicon

Boron has 3 valence electrons, while silicon has 4. When boron is doped into silicon, it acts as an acceptor and produces a p-type semiconductor, so holes become the majority carriers.