Question

Explain the term ‘drift velocity’ of electrons in a conductor. Hence obtain the expression for the current through a conductor in terms of ‘drift velocity’.

Answer 1

Drift velocity : It is the average velocity acquired by the free electrons superimposed over the random motion in the direction opposite to electric field and along the length of the metallic conductor.

Let n = number of free electrons per unit volume, v_d = Drift velocity of electrons Total number of free electrons passing through a cross section in unit time

N/t = Anv_d

So, total charge passing through a cross section in unit time

i.e., current, l = Q/t = N/t = Anev_d.