Calculate the drift speed of the electrons when 1A of current exists in a copper wire of cross section 2 `mm^(2)`.The number of free electrons in `1cm^(3)`of copper is `8.5xx10^(22)`.

Explanation

we have
`j=nev_(d)`
or, `v_(d)=j/n e=i/A ne`
`(1A)/((2xx10^(-6)m^(2))(8.5xx10^(22)xx10^(6)m^(-3))(1.6xx10^(-19)C))`
`=0.036mm s^(-1)`.
We see that the drift speed is indeed small.