Question

Why does the resistance of a metallic conductor increases with increase in temperature 0th?

Answer 1

The flow of electrons is sometimes slowed down by the collision with vibrating atoms.If you increase the temperature of the conductor the number of phonons will increase, thus resulting in more collisions. The increase of the number or probability of collisions results in the increase of resistance of the conductor.

Answer 2

$\bf Hey\:There\:!$

The resistance of a conductor increases with an increase in temperature because the thermal velocity of the free electrons increase as the temperature increases. This results in an increase in the number of collisions between the free electrons.