Question

Resistance of conductor increases with rise in temperature because

• A. due to thermal expansion increase in length is more than increase in area.
• B. with rise in temperature speed of electrons increases due to which resistivity decreases.
• C. with rise in temperature speed of electrons increases due to which conductivity decreases.
• D. none

Answer 1

The correct option is C with rise in temperature speed of electrons increases due to which conductivity decreases.

Conductivity $=\frac{n{e}^2\tau }{m}$
When temperature increases, speed increases and $\tau$ decreases and hence conductivity decreases.