Question

Across a conductor of length $40\text{cm}$, a potential difference of $10\text{V}$ is maintained. The mobility of electrons if the drift velocity of electrons is $5\times {10}^{-6}\text{m/s}$ is

• A. $2\times {10}^{-7}{\text{m}}^2\text{/Vs}$
• B. $1\times {10}^{-7}{\text{m}}^2\text{/Vs}$
• C. $4\times {10}^{-6}{\text{m}}^2\text{/Vs}$
• D. $0.5\times {10}^{-7}{\text{m}}^2\text{/Vs}$

Answer 1

The correct option is A $2\times {10}^{-7}{\text{m}}^2\text{/Vs}$

Given:
$v_d=5\times {10}^{-6}\text{m/s};$
$V=10\text{V};l=40\text{cm}=0.4\text{m}$

From definition of mobility,

$\mu =\frac{v_d}{E}$

$\Rightarrow \mu =\frac{v_{d}l}{V}(\because E=V/l)$

putting the value

$\Rightarrow \mu =\frac{5\times {10}^{-6}\times 0.4}{10}$

$\therefore \mu =2\times {10}^{-7}{\text{m}}^2\text{/Vs}$

Hence, option $\left(a\right)$ is correct