What is the resistivity of the metal if its length is 2m,the resistance is 20 ohm and the diameter is given as 0.03 mm

Dear Student,

The electrical resistivity $\rho$ of a conducting material is given by


$\rho = R\frac{A}{l}$   (1), where R is the resistance of the material of length l and area of cross section A and A = $\pi r^2$, r is the radius of the wire.

Here r = 0.03/2 = 0.015 mm or 15$\times$10^-6 m



$\rho$ = 20$\times \frac{\pi \times {\left(15\times {10}^{-6}\right)}^2}{2}$ = 7.07$\times$10^-9 $\Omega$m


Regards