Question

For an insulator, the forbidden energy gap is ______.

Options

• zero

• 1 eV

• 2 eV

• 5 eV

Answer 1

For an insulator, the forbidden energy gap is 5 eV.

Explanation:

For an insulator, E_g > 3 eV, i.e. why electron transition from the valence band to the conduction band is not possible. For semiconductors, E_g is near about 1 eV while for metals E_g = 0 eV.