Consider steady heat transfer between two large parallel plates at constant temperature of T, 300 k, and T₂ 200 k, L=1 cm apart. Assuming the surfaces to be black bodies (E-1). Determine the heat flux between the plates, assuming the gap between the plates is: (a) filled with air (k-0.0219 W/m k) (b) Evacuated (c) Filled with Insulation (k=0.026 W/m k)