Q 12-03-131JEE MainJEE Main 2023 (25 Jan, Shift 2)Easy
The resistance of a wire is $5\ \Omega$. Its new resistance in ohm, if stretched to $5$ times of its original length will be
Answer: (B) 125
At constant volume $R\propto l^2$: $R'=5\times25=125\ \Omega$.
Solution by Sreeraj P, M.Sc Physics