Question

For an insulator, the forbidden energy gap is

• A. $1MeV$
• B. $0.1MeV$
• C. $1eV$
• D. $5eV$

Answer 1

The correct option is D

$5eV$

To find the forbidden energy gap of an insulator

1. The forbidden energy gap, also known as the band gap refers to the energy difference between the top of the valance band and the bottom of the conduction band.
2. Current flowing through the material is due to the electron transfer from the valence band to the conduction band.
3. Insulators do not conduct electricity because a large amount of energy is needed for the electron to cross the forbidden energy gap.
4. It is greater than $5eV$.
5. Hence for an insulator the forbidden gap is greater than $5eV$

Therefore Option D is the correct answer.