Question

When two same conducting rod are kept at different temperature,

• A. theirs resistivity will be different
• B. their resistivity will be same
• C. resistivity doesn't depend on temperature
• D. none of the above

Answer 1

The correct option is A theirs resistivity will be different

Resistivity of metallic conductor increases with increase in temperature. When temperature is increased for the metallic conductor, its constituent atoms vibrate with greater amplitudes than usual which leads to frequent collison between ions and electrons. As a result average time between the two successive collision decreases resulting in the decrease in drift velocity. Thus increase in collison with the increase in tempearture results in increasing resistivity.
For small temperature variations resistivity of the most of the metals varies according to the following relations:
$\rho \left(T\right)=\rho \left(T_0\right)[1+\alpha (T-T_0\left)\right]$
Where $\rho \left(T\right)$ and $\rho \left(T_0\right)$ are the resistivies of the material at temperature $T$ and $T_0$ respectively and $\alpha$ is known as coefficient of resistivity.