Q 12-03-087JEE MainJEE Main 2024 (27 Jan, Shift 2)Easy
Wheatstone bridge principle is used to measure the specific resistance $S_1$ of a given wire, having length $L$ and radius $r$. If $X$ is the resistance of the wire, then specific resistance is $S_1 = X\dfrac{\pi r^2}{L}$. If the length of the wire gets doubled, then the value of specific resistance will be:
Answer: (D) $S_1$
Specific resistance (resistivity) is a property of the material only. Doubling the length doubles $X$, and $X\pi r^2/L$ remains unchanged, so it stays $S_1$.
Solution by Sreeraj P, M.Sc Physics