The drift velocity of electrons in a copper wire of length 2 m under the application of a potential difference of 200 V is $0.5 ms^{-1}$. The mobility of electrons in $m^2 V^{-1} s^{-1}$ is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $5.0 \times 10^{-3}$
$v_d=μE$ [formula]
where,
$v_d$ = drift velocity = 0.5 m/s
$μ$ = mobility of electrons
E = electric field (v/m)
and,
$E=\frac{V}{L}$
where,
V = Potential difference = 200 V
L = length of wire = 2 m
$E=\frac{V}{L}=\frac{200}{2} = 100V/m$
and,
$v_d=μE$
$μ=\frac{0.5}{100}$
$=5.0 \times 10^{-3}m^2/Vs$