please help step by step
phym316 mc 139%. question 4 (25 marks) Consider a metal bar with square cross-section that is 10 cm long and 1 cm wide. A potential difference of 250 V is applied across its ends. It has a resistivity of 10-8 2m and electron density of 6 x 10sm-3 (a) Calculate the relaxation time, T. (b) Calculate the shift in the Fermi surface due to the applied voltage. [51 15] (d) What is the thermal conductivity...