Q 11-08-055JEE MainJEE Main 2023 (15 Apr, Shift 1)Easy
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 same material of length $2L$ and radius $2r$ is pulled by a force $2f$. Then the increase in its length will be
Answer: (D) $l$
$\Delta L=\dfrac{FL}{\pi r^2Y}\propto\dfrac{FL}{r^2}$: factor $\dfrac{2\times2}{4}=1$, so the increase is $l$.
Solution by Sreeraj P, M.Sc Physics