A diffuse radiating oven wall has a temperature T = 500 K and a spectral emissivity approximated by the following function: The oven wall is exposed to radiation from glowing coal; the spectral...

A diffuse radiating oven wall has a temperature T = 500 K and a spectral emissivity approximated by the following function:

The oven wall is exposed to radiation from glowing coal; the spectral irradiance E_λ
can be assumed to be proportional to the hemispherical spectral emissive power M_λs(TK) of a black body at T_K
= 2000 K.

a) Calculate the total emissivity ε of the oven wall.

b) Calculate the total absorptivity a of the oven wall for the radiation emitted by the coal.