A cylindrical wire of copper having area of cross section `2.5mm^(2)` is carrying 1 A current. The wire is strethced so that its area of cross section becomes 1.25 `mm^(2)`. How does the mobility of charge carrier will change if te 4 A current is passed through the wire.

Options

A. Mobility will remain same
B. Mobility will become 4 times
C. Mobility will become 8 times
D. Mobility will become half

Answer

A

Explanation

mobility `mu=(V_(d))/(E)`
`v_(d)=(I)/(n eA)=(J)/(n e)`
`mu=(J)/(En e)=(sigma)/(n e)`
Which is independent of current or area.