Calculation of the Lorenz number, 

(a) Application of kinetic theory to the "electron gas" in a metal³ gives for the Lorenz number L = π2/3(K/e)² in which K is the Boltzmann constant and e is the charge on the electron. Compute L in the units given under Eq. 9.5-1. 

(b) The electrical resistivity, 1/k_e, of copper at 20^oC is 1.72 x 10^-6ohm ∙ cm. Estimate its thermal conductivity in W/m o K using Eq. 9A.6-1, and compare your result with the experimental value given in Table 9.1-4.