Question

A potential difference of 5 V applied across a conductor of length 10cm. If drift velocity of electrons is 2.5 ${\times 10}^{-4}$ m/s, then electron mobility will be

• A. ${5\times 10}^{-4}{m}^2{V}^{-1}{s}^{-1}$
• B. ${5\times 10}^{-6}{m}^2{V}^{-1}{s}^{-1}$
• C. ${5\times 10}^{-2}{m}^2{V}^{-1}{s}^{-1}$
• D. zero

Answer 1

The correct option is B ${5\times 10}^{-6}{m}^2{V}^{-1}{s}^{-1}$

If the potential difference is $5V$ across the conductor of length of $10cm$ or $0.1m$ then,

Electric field, $E=\frac{Potentialdifference}{Distance}$

$=\frac{5}{0.1}V/m=50V/m$

Now, mobility $=\frac{u}{E}$

where,

$u=$ Drift velocity $=2.5\times {10}^{-4}m/s$

So, Mobility $=\frac{2.5\times {10}^{-4}}{50}=5\times {10}^{-6}{m}^2{V}^{-1}{s}^{-1}$