Question

A copper wire carries a current of density j = 1.0 A/mm². Assuming that one free electron corresponds to each copper atom, evaluate the distance which will be covered by an electron during its displacement l = 10 mm along the wire.

Answer 1

By definition

n e v_d = j (where v is drift velocity, n is number density of electrons.)

So distance actually travelled

( <v> = mean velocity of thermal motion of an electron)