The potential difference between two points in a wire 8.0 m apart is 8.0 V when the current density is 4.0 x 107 Am–2. The resistivity of the material is
Answer & explanation
Correct answer: option 3
$ E = \frac{V}{d} = 1 V/m$
$ \rho = \frac{E}{J} = \frac{1}{4\times 10^7} = 2.5\times 10^{-8} \Omega -m$