Question

1. An unknown wire experiences an electric field of 10 V/m, and has a current density of 5.0 ✕ 10⁷ A/m² . What is the resistivity of the wire?

Answer 1

Given:

$E=\rm 10\: V/m$

$j=\rm 5.0*10^7\: A/m^2$

The Ohmn law says

$$j=\sigma E=\frac{1}{\rho}E$$

Hence, the resistivity of a wire

$$\rho=\frac{E}{j}=\frac{10}{5.0*10^7}=2.0*10^{-7}\:\rm \Omega\cdot m$$