Question

Find the velocity of charge leading to `1A` current which flows in a copper conductor of cross section `1cm^2` and length `10 km`. Free electron density of copper is `8.5x10^28//m^3`. How long will it take the electric charge to travel from one end of the conductor to the other?

Answer 1

Correct Answer - A::C::D
From`i="ne"Av_d`
We have `v_d=1/("ne"A)`
or `V_(d) = 1/(8.5xx10^28xx1.6xx10^-19xx10^-4)`
`=0.735xx10^-6m//s`
`=0.735mum//s`
`t=1/v_d`
`=(10xx10^3)/(0.735xx10^-6)s`
`=(10xx10^3)/(0.735xx106-6xx60xx60xx24xx365)yr`
`=431.4yr`