Q. If the free electron density be $n$ and relaxation time be $\tau$, the electrical conductivity of a conductor may be expressed as
A) $\frac{ne\tau}{m_{e}}$
B) $\frac{ne^{2}\tau}{m_{e}}$
C) $\frac{ne^{2}}{\tau m_{e}}$
D) $\frac{m_{e}e^{2}\tau}{n}$
Explanation
(b) Resistivity, $\rho = \frac{m_{e}}{ne^{2}t}$
Conductivity, $\sigma = \frac{1}{p} = \frac{ne^{2}\tau}{m_{e}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.