Question

Calculate the drift velocity of free electrons if a current of 5 A is maintained in a conductor of cross-section 10^-2m^2. The number density of free electrons is 5 × 10^20m^-3.

(a) 6.25 ms^-1

(b) 5.25 ms^-1

(c) 2.25 ms^-1

(d) 12.25 ms^-1

I had been asked this question during an online interview.

This interesting question is from Current Electricity topic in division Current Electricity of Physics – Class 12

Answer 1

Right option is (a) 6.25 ms^-1

The best explanation: Drift velocity = \(\frac {Current}{(number \, density \, of \, electrons \, \times \, charge \, on \, electron \, \times \, Area)}\).

\(\frac {5}{(5 \times 10^{20} \times 1.6 \times 10^{-19} \times 10^{-2})}\)

= 6.25 ms^-1.