4) Consider a hemicylindrical furnace of length L = 20 m with a flat base, as shown in the figure. The base and the hemicylindrical dome of the furnace are black body and they are maintained at uniform temperatures of 400 K and 1000 K, respectively. Front and back surfaces of the furnace (surface 3 and surface 4) are reradiating surfaces and they are at 400 K. As known, these idealized surfaces are characterized by zero net radiation transfer (q3=q4= 0). Making some assumptions and by drawing thermal radiation resistance circuit, calculate the net rate of radiation heat transfer from the dome to the base during steady-state operation, q21. = 1