Question

The energy gap in a conductor at room temperature is ____.

• A. greater than that in a semiconductor
• B. less than that in a insulator
• C. greater than that in a insulator
• D. Both (A) and (B) are true

Answer 1

The correct option is B less than that in an insulator

The energy band gap is the energy difference between the valence band and the conduction band. In case of conductors, the valence band is partially filled and it overlaps with the conduction band so the energy band gap is very small almost equal to zero, whereas, in case of insulators, the valence band is full, so perturbation within the band is impossible and the electrons in the valence band are separated by a large energy gap from the conduction band. Thus, electrons cannot be promoted to an empty level where they could move freely. Hence, very small or negligible conductivity is observed.

Band gap of semiconductore is intermediate between conductor and insulator.
So, band gap of conductors is less than insulators and semiconductors.
Electrical conductivity of metals

Electrical conductivity of semiconductors


Electrical conductivity of insulators