A diffuse surface having the following spectral characteristics is maintained at 500 K when situated in a large furnace enclosure whose walls are maintained at 1500 K:

  (a) Sketch the spectral distribution of the surface emissive power E_λ and the emissive power E_λ.b that the surface would have if it were a blackbody.

  (b) Neglecting convection effects, what is the net heat flux to the surface for the prescribed conditions?

  (c) Plot the net heat flux as a function of the surface temperature for 500 < T < 1000 K. On the same coordinates, plot the heat flux for a diffuse, gray surface with total emissivities of 0.4 and 0.8.

  (d) For the prescribed spectral distribution of ɛ_λ, how do the total emissivity and absorptivity of the surface vary with temperature in the range 500 < T < 1000 K?