Question

Temperature dependence of resistivity $\rho \left(T\right)$ of semiconductors, insulators and metals is significantly based on the following factors

• A. number of charge carriers can change with temperature T
• B. time interval between two successive collisions can depend on T
• C. length of material can be a function of T
• D. mass of carries is a function of T

Answer 1

Answer: (A), (B)

The correct options are
A number of charge carriers can change with temperature T
B time interval between two successive collisions can depend on T

We know that resistivity ( $\rho$ ) depends on mass of charge-carrier (m), relaxation time ( $\tau$ ). Length and mass cannot be function of T as the mass of a body is constant everywhere. So discards answer (d) and length of body changes negligibly with temperature discards answer (c).
As $\tau$ decreases on increasing $T$ due to the rise in the speed of change-carriers and $n$ increases on increasing temperature. So will affect the $\rho$ or $\rho$ is the function of $T$ verifies answers (a) and (b)