Question

A potential difference of 100 V is applied across a conductor of length 50cm. Calculate the drift velocity of electrons if the electron mobility is 9 × 10^-5 m^2V^-1s^-1.

(a) 0.001 ms^-1

(b) 1.800 ms^-1

(c) 0.018 ms^-1

(d) 0.180 ms^-1

The question was posed to me during an interview.

Question is from Current Electricity in section Current Electricity of Physics – Class 12

Answer 1

Correct answer is (c) 0.018 ms^-1

Easiest explanation: Drift velocity = Mobility × Electric field.

It can be rearranged as,

Drift velocity = \(\frac {(mobility \, \times \, Potential \, difference)}{length}\).

Drift velocity = \(\frac {(9 × 10^{-5} \times 100)}{0.5}\) = 0.018 ms^-1.