Calculate the relaxation time and mean free path at room temperature (i.e. `27^(@)C`). If the number of free electrons per unit volume is `8.5 xx 10^(28)//m^(3)` and resistivity `rho = 1.7 xx 10^(8) Omega-m`. Given that mass of electron `= 9.1 xx 10^(-31) kg`
`e = 1.6 xx 10^(-19)C and k = 1 .36 xx 10^(-23) JK^(-1)`