Question

Resistance of a metal wire of length $1m$ is $104\Omega$ at $20C$. If the diameter of the wire is $0.15mm$, find the resistivity of the metal at that temperature.

Answer 1

Formula,

$R=\frac{\rho l}{A}$

$\Rightarrow \rho =\frac{RA}{l}$

$=\frac{R\pi d^2}{4l}$

$\rho =\frac{104\times 3.14\times {0.0015}^2}{4\times 1}$

$\therefore \rho =1.84\times {10}^{-4}\Omega$