Q 12-03-164JEE MainJEE Main 2022 (25 Jun, Shift 2)Easy
The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be ______ %.
Numerical value type. Enter your answer.
Answer: 300
The volume stays constant, so $A\propto\dfrac1l$ and $R = \dfrac{\rho l}{A}\propto l^2$. Doubling $l$ makes $R' = 4R$, an increase of $300\%$.
Solution by Sreeraj P, M.Sc Physics