Define the term electrical resistivity of a material. Write the S.I units. Derive an expression for the resistivity of a metal in terms of number density and mass of free electrons present in it .

Question

$\begin{array}{1 1} \text{a. $ \rho=\frac{m}{ne^2T}$} \\ \text{b. $\rho = \frac{mn}{e^2T}$} \\ \text{c. $\rho = \frac{ne^2T}{m}$} \\ \text{d. $\rho = \frac{e^2T}{mn}$} \end{array}$