A copper wire has `3xx 10^(22)` free electrons in `0.021 m` length. The drift velocity of electrons is found to be `2xx10^(-5)ms^(-1)`.
How large a current will flow through the wire?

Explanation

Given:
`N=(3xx10^(22))/(0.021)=1.429xx10^(24)` electrons/m.
`v_(d)=2xx10^(-5)ms^(-1)`
But number density `n=(N/A)` so that nA = N.
Since, `I=nAev_(d)`
We get, `I=Nev_(d)`
i.e., `I=(1.429xx10^(24))(1.6xx10^(-19))(2xx10^(-5))A`