Engineering Physics

Calculate the mean free time and mean free path between the collisions for the free electrons in copper with number density of the electron $8.5\times10^{28},\mathrm{m^{-3}}$ and resistivity $1.7\times10^{-8},\mathrm{\Omega\text{-}m}$.($e=1.6\times10^{-19},\mathrm{C}$, $m_{e}=9.1\times10^{-31},\mathrm{kg}$ and effective speed of the electron = $1.6\times10^{6},\mathrm{m/s}$)