Calculate the average drift speed of conduction electrons in a copper wire of cross-sectional area `1.0xx10^(-7)m^(2)`, carrying a current of 1.5 A. Assume that each copper atom contributes roughly one conduction electron. The density of copper is `9.0xx10^(3) kg m^(-3)` and its atomic mass is 63.5. Take Avogadro's number `=6.0xx10^(23)`.

Options

A. `1.1xx10^(-2) ms^(-1)`
B. `1.1xx10^(-3) ms^(-1)`
C. `2.2xx10^(-2) ms^(-1)`
D. `2.2xx10^(-3) ms^(-1)`

Answer

B

Explanation

Here, density of copper `(rho)=9xx10^(3)kgm^(-3)`,
Avogadro's number `(N)=6.023xx10^(23)`.
Atomic mass of copper `(m)=63.5 g = 63.5xx10^(-3)kg`
Number of free electrons per unit volume,
`n=(N)/(m)rho = (6.023xx10^(23))/(63.5xx10^(-3))xx9xx10^(3)`
Drift velocity, i.e.,
`v_(d)=(i)/("nAe")=(1.5xx63.5xx10^(-3))/(6.023xx10^(23)xx9xx10^(3)xx10^(-7)xx1.6xx10^(-19))`
`=1.1xx10^(-3)ms^(-1)`