Consider a flat black body, with a surface area of 1 m', placed on the ground and receiving through its upper face a flux of solar radiation of 1000 W. 1- Calculate, neglecting the phenomena of conduction and convection, the temperature of the black plane body at thermal equilibrium. 2- A glass plate is placed parallel to the flat black body to cause a greenhouse effect. The transmission spectrum of the glass used shows that all wavelengths below 3 jum are fully transmitted. On the other hand, beyond 3 um, the glass used behaves like a perfect absorber. a- Show that solar radiation is almost completely emitted with wavelengths less than 3 um and that that of the black plate (initially assumed to be equal to 500K) is almost completely emitted above 3um.