The number of free electrons per 100 mm of ordinary copper wire is `2xx10^(21)`. The average drift speed of electorn is `0.25 mm//s`. What is the current flowing?

Options

A. `5 A`
B. 80 A
C. `8 A`
D. `0.8 A`

Answer

D

Explanation

Number of electrons per unit volume-
`n = (2 xx 10^(21))(A xx 100)`
`I = "ne"Av_(d) = (2 xx 10^(21))(A xx 100) xx 1.6 xx 10^(-19) xx A xx 0.25`
`rArr I = 0.8 A`