A rectangular copper bus bar (k = 400 W/m·K), 10 mm × 200 mm × 3 m, carries 5000 A; resistance 2 × 10^{−5} Ω. The two 3 m × 200 mm faces are exposed to air at 22 °C with h = 5 W/m^{2}·K. Find (a) the volumetric heat generation (answer in kW/m^{3}) and (b) the surface temperature (answer in °C).