The coating on aim by 2 m metallic surface is cured by placing it 0.5 m below an electrically heated surface of equivalent dimensions, and the assembly is exposed to large surroundings at 300 K. The heater is well insulated on its top side and is aligned with the coated surface. Both the heater and coated surfaces may be approximated as blackbodies. During the curing procedure, the heater and coated surfaces are maintained at 700 and 400 K, respectively. Convection effects may be neglected.

(a) What is the electric power, qelec' required to operate the heater?

(b) What is q_elec if the surfaces are connected with reradiating sidewalls?

(c) The facility may be used to cure different surface coatings. With the heater still approximated as a blackbody, compute and plot qelec as a function of the coating's emissivity for values ranging from 0.1 to 1.0. Perform the calculations for both open and reradiating sides.

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Heated surface 105 m Coated surface Surroundings