A uniform copper wire of length `1m` and cross section area `5 xx 10^(-7)m^(2)` carries a current of `1A`. Assuming that are `8 xx 10^(28)` free electron per `m^(3)` in copper, how long will an electron take to drift from one end of the wire an electron the other. Charge on an electron `= 1.6 xx 10^(-19)C`

Options

A. `1.6 xx 10^(3)s`
B. `3.2 xx 10^(3)s`
C. `6.4 xx 10^(3)s`
D. `8.0 xx 10^(3)s`

Answer

c

Explanation

Here `l = 1m, A = 0.5 xx 10^(-6)m^(2) = 5 xx 10^(-7)m^(2)`
`n = 8 xx 10^(22) cm^(-3) = 8 xx 10^(28)m^(-3), 1 = 1A`
`v_(d) = (1)/(nAe)`
Time `t = (1)/(v_(d)) = (l n Ae)/(1)`
`=(1 xx (8 xx 10^(28) ) xx (5 xx 10^(-7)) xx 1.6 xx 10^(-19))/(1)`
`= 6.4 xx 10^(3)s`