The number density of conduction electrons in a copper conductor is `8.5xx10^(28) m^(-3)`. How long does an electron take to drift from one end of a wire 3.0 m long to its other end ? The area of cross-section of the wire is `2.0xx10^(-6) m^(2)` and it is carrying a current of 3.0 A.

Explanation

We can first calculate drift velocity of the electrons from the given data.
`I=An ev_(d)`
`3=2xx10^(-6)xx8.5xx10^(28)xx1.6xx10^(-19)v_(d)`
`v_(d)=0.11xx10^(-3)ms^(-1)`
Now, time taken by an electron to drift a length of 3 m with drift speed `v_(d)`,
`t=(l)/(v_(d))=(3)/(0.11xx10^(-3))=27.27xx10^(3)s`.