Question

What happens to relaxation time in conductor with increase in temperature?

Answer 1

when the temperature increases the number of collisions of the electrons in the conductor increases.This reduces the relaxation time of the electrons. Relaxation time is directly proportional to the drift velocity as:

 Vd = -(eE/m)τ  where τ is the relaxation time and  Vd is the drift velocity.

so as the relaxation decreases, the drift velocity also decreases .