A copper wire carries a current of density `f = 1.0 A//mm^(2)`. Assuming that one free electron corresponds to each cooper atom, evalutea the distance which will be covered by an electron during its displacement `l = 10mm` along the wire.

Explanation

By defination
`n e v_(d) = j` (where `v_(d)` is the drift velocity, `n` is number density of electrons.)
Then `tau = (1)/(v_(d)) = (n e l)/(j)`
So distance acutually travelled
`S = lt v gt tau = (n e l lt v gt)/(j)`
(`lt v gt` = means velocity of thermal motion of an electron)