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. `1.1 ms^(-1)`
B. `0.11 mms^(-1)`
C. `1.1 mms^(-1)`
D. `11 ms^(-1)`

Answer

C

Explanation

Given, `e=1.6xx10^(-19)C, A = 1.0xx10^(-7)m^(2)`,
`l = 1.5 A`.
A cubic metre of copper has a mass of `9.0xx10^(6)`
`= 8.5xx10^(28)m^(-3)`
The drift speed `v_(d)` is given by
`v_(d)=(I)/("n e A")`
`v_(d)=(1.5)/(8.5xx10^(28)xx1.6xx10^(-19)xx1.0xx10^(-7))`
`= 1.1xx10^(-3)ms^(-1)=1.1 mms^(-1)`