Question

The energy gap between the valence band and the conduction band for the material is $>9eV$. Identify the material.

• A. An insulator
• B. A metal
• C. An intrinsic semiconductor
• D. A superconductor

Answer 1

Answer: (A)

An insulator

The energy gap is the difference between energies corresponding to the electrons valance band and conduction band.

Free electrons present in conduction band, conducts the energy in the materials.

In metals, valance band and conduction bands overlaps with each other.

In semiconductors, energy gap is small, i.e. when temperature rises, the excited electrons can achieve conduction band.

In insulators, the energy gap is more than 5eV, i.e. if temperature rises higher the valance electrons are not able to achieve conduction band.

Therefore, the given material is an insulator.

Hence, correct answer is option A.