A wire of length L and radius r is clamped rigidly at one end. When the other end of the wire is pulled by a force f, its length increases by l. Another wire of the same material of length 2L and radius 2r, is pulled by a force 2f. Find the increase in length of this wire.

Options

A. `l/2`
B. `l`
C. `2l`
D. `l/4`

Answer

B

Explanation

`Y=(F//A)/(/_\l//l)`
For the first wire `Y=(FxxL)/(pir^(2)xxl)`
For the second wire `Y=(2Fxx2L)/(pi(2r)^(2)xxl')`
From the above two equuations `l'=1`