A circular plate of 500-mm diameter is maintained at T1 = 600 K and is positioned coaxial to a conical shape. The back side of the cone is well insulated. The plate and the cone, whose surfaces are black, are located in a large, evacuated enclosure whose walls are at 300 K.

(a) What is the temperature of the conical surface, T2?

(b) What is the electrical power that would be required to maintain the circular plate at 600K?

For part a)

Since the conical surface is not exposed to the radiation coming from the walls only from the circular plate and assuming steady state, the temperature of the conical surface is also equal to the temperature of the circular plate. T2 = 600 K

For part b)

To maintain the temperature of the circular plate, the power required would be calculated using:

Q = Aσ (T₁⁴ - Tw⁴)

Q = π (500x10^-3) ²/4 (5.67x10^-8) (600⁴ - 300⁴)

Q = 5410.65 W