The resistivity of a conductor in which a current density of \( 3.5\,\mathrm{A\,m^{-2}} \) is found to exist on applying an electric field of \( 28\,\mathrm{V\,m^{-1}} \) will be
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( 8\,\Omega\,\mathrm{m} \)
In the vector form of Ohm's law, the electric field is the resistivity times the current density.
\( \displaystyle E = \rho\,j \;\Rightarrow\; \rho = \frac{E}{j} \)
\( \displaystyle \rho = \frac{28\,\mathrm{V\,m^{-1}}}{3.5\,\mathrm{A\,m^{-2}}} = 8\,\Omega\,\mathrm{m} \)