Question

Electrical conductivity of metals decreases with rise in temperature whereas in semiconductors it increases with rise in temperature. Explain

Answer 1

with increase in temperature the distance between the conduction and valence band increases and therefore electrons can't jump from the valence band to te conduction band

Answer 2

$\huge\bold{\green{Answer :-}}$

$\bigstar\:\underline{\bold{\pink{Case (1) :} Metals\implies}}$

The electrical conductivity of metal is due to the migration of free mobile electrons under the influence of applied potential difference.

On heating, the cores or kernels start vibrating and they cause hindrance to the directed flow of electrons. Therefore the electrical conductivity of the metals decreases.

$\bigstar\:\underline{\bold{\pink{Case (2) :} Semi-conductor\implies}}$

The electrical conductivity of semi-conductors increases with the increase in temperate. This happens because with the increase in temperature, the number of free electrons and the positive holes increases due to the internal release of electrons upon heating.