Question

The electrical conductivity of monovalent Na metal is 117m1017.2−−Ω×. Calculate the relaxation time and the drift velocity in a field of 100 V m−1. Take density of Na to be 0.97 gm cm−3.

Answer 1

Following Lorentz-Drude theory the relaxation time equals to 

$$\tau=(2m/e^2Na)(\sigma\mu/\rho)$$

i.e. 0.033 (s). The drift velocity respectively is 

$$v=(E/eNa)(\sigma\mu/\rho)$$

or 2.9*10¹¹ (m/s).