Chapter 12, Problem 12.129P

Two plates, one with a black painted surface and the other with a special coating (chemically oxidized copper) are in earth orbit and are exposed to solar radiation. The solar rays make an angle of ${30}^{\circ }$ with the normal to the plate. Estimate the equilibrium temperature of each plate assuming they are diffuse and that the solar flux is $1368{\text{ W/m}}^2$ . The spectral absorptivity of the black painted surface can be approximated by ${\alpha }_{\lambda }=0.95\text{ for 0}\le \lambda \le \infty$ and that of the special coating by ${\alpha }_{\lambda }=0.95\text{ for 0}\le \lambda <3\mu m$ and. ${\alpha }_{\lambda }=0.05\text{ for }\lambda \ge 3\mu m$ .