1.a) Calculate the heat flux emitted due to thermal radiation from a black surface at (a) 6000K and (b) 600K. At what wavelength is the monochromatic emissive power maximum and what is the maximum value? Compare the answers for the two cases. b) Estimate the rate at which the sun emits radiant energy. W hat fraction of this energy is intercepted by the earth and what is the amount intercepted? Given: (i) the effective temperature of the sun's surface is 5770K; (ii) the surface is black; (iii) diameter of sun =1.39106km; (iv) diameter of earth =1.27104km and (v) distance between the sun and the earth =1.5108km c)The monochromatic emissivity of a surface varies with wavelength in the manner shown in Fig. Make a suitable approximation and calculate the emissivity of the surface if its temperature is 2000K