Consider a wire of length 4m and cross - sectional area `1mm^(2)` carrying a current of 2A. If each cubic metre of the material contains `10^(29)` free electrons, find the average time taken by an electron to cross the length of the wire.

Explanation

`rArr v_(d)=(i)/(nAe)=(2)/(10^(29)xx10^(-6)xx1.6xx10^(-19))ms^(-1)`
`=12.5xx10^(-4)ms^(-1)`
`rArr" Average time takne by an electron to cross the length of wire"`
`t=(1)/(v_(d))=(4)/(1.25xx10^(-4))s=3.2xx10^(4)s`