Embibe Experts Solutions for Chapter: Electric Current Through Conductors, Exercise 1: MHT-CET 2018

The resistivity of potentiometer wire is $40\times {10}^{-8} \mathrm{\Omega } \mathrm{m}$ and its area of cross-section is $8\times {10}^{-6} {\mathrm{m}}^2$. If $0.2 \mathrm{A}$ current is flowing through the wire, the potential gradient of the wire is

A conducting wire has length $L_1$ and diameter $d_1$. After stretching the same wire length becomes $L_2$ and diameter $d_2$ . The ratio of resistance before and after stretching is