Question

In terms of band theory, what is the difference

(i) Between a conductor and an insulator ?

(ii) Between a conductor and a semiconductor ?

Answer 1

(i) The energy gap between the valence band and conduction band in an insulator is very large while in a conductor, the energy gap is very small or there is overlapping between valence band and conduction band.

(ii)

In a conductor, the valence band is practically filled or there is overlapping between valence band and conduction band while in semiconductor, there is always a small energy gap between them.