Steel and copper wires of same length are stretched by the same weight one after the other. Young's modulus of steel and copper are `2xx10^(11)(N)/(m^2)` and `1.2xx10^(11)(N)/(m^2)`. The ratio of increase in length is

Options

A. `(2)/(5)`
B. `(3)/(5)`
C. `(5)/(4)`
D. `(5)/(2)`

Answer

B

Explanation

`l=(FL)/(AY)implies(l_s)/(l_(cu))=(Y_(cu))/(Y_s)`
`(l_S)/(l_(cu))=(1.2xx10^(11))/(2xx10^(11))=(3)/(5)`