Q 12-03-128JEE MainJEE Main 2023 (24 Jan, Shift 2)Easy
If a copper wire is stretched to increase its length by $20\%$, the percentage increase in resistance of the wire is ______ %.
Numerical value type. Enter your answer.
Answer: 44
Volume is constant, so $R=\dfrac{\rho l}{A}=\dfrac{\rho l^2}{V}\propto l^2$. $R'=(1.2)^2R=1.44R$: an increase of $44\%$.
Solution by Sreeraj P, M.Sc Physics