A current of 2 A is passing through a metal wire of cross sectional area `2 xx 10^(-6) m^(-2)` . If the number density of free electrons in the wire is `5 xx 10^(26) m^(-3)` , the drift speed of electrons is (given `e = 1.6 xx 10^(-19) C)`

Options

A. `(1)/(16) ms^-1`
B. `(1)/(40) ms^(-1)`
C. `(1)/(80) m s^(-1)`
D. `(1)/(32) ms^(-1)`

Answer

C

Explanation

Here , Current I = 2 A
Area of cross-section , `A = 2 xx 10^(-6) m^(2)`
Number density of free electrons , `n = 5 xx 10^(26) m^(-3)`
The drift speed of electrons is `v_(d) = (1)/(n A e) = (2 A)/((5 xx 10^(26) m^(-3)) (2 xx 10^(-6) m^(2)) (1 .6 xx 10^(-19) C))`
= `(1)/(80) ms^(-1)`