A current of 1.34A exists in a copper wire of cross-section `1.0mm^(2)`. Assuming each copper atom contributes one free electron. Calculate the drift speed of the free electrons in the wire. The density of copper is 8990 `kg// m^(3)` and atomic mass=63.50.

Explanation

Mass of `1m^(3)` volume of the copper is `=8990 kg=8990xx10^(3)g`
Number of moles in `1m^(3)=(8990xx10^(3))/(63.5)=1.4xx10^ (5)`
Since each mole contains `6xx10^(23)` atoms therefore number of atoms in `1m^(3)`
`n=(1.4xx10^(5))xx(6xx10^(23))`
`=8.4xx10^(28)`
` i="ne"Av_(d)`
`v_(d)=(1)/("ne"A)=(1.34)/(8.4xx10^(28) xx1.6 xx10^(-19)xx10^(-6)) (because 1mm^(2)=10^(-6)m^(2))`
`=10^(-4)m //"sec"`.
`=0.1 mm//"sec"`.