Question

If $n, e, \tau$ and $m$ are representing electron density, charge, relaxation time and mass of an electron respectively, then the resistance of a wire of length $l$ and cross-sectional area $A$ is given by

• A. $\frac{m l}{n e^{2} \tau A}$
• B. $\frac{m \tau A}{n e^{2} l}$
• C. $\frac{n e^{2} \tau A}{m l}$
• D. $\frac{n e^{2} A}{m \tau l}$

Answer 1

Answer: (A)

$R=\frac{P I}{A}$
$R=\frac{m l}{n e^{2} l A}$