For a perfectly black body,its absorptive power is

Surface temperature of the sun is of the order of $K$.

For an opaque body,the coefficient of transmission is:

The temperature of the sun is measured with:

Three very large plates of the same area are kept parallel and close to each other. They are considered as ideal black surfaces and have very high thermal conductivity. The first and third plates are maintained at temperatures $2\ T$ and $3\ T$ respectively. The temperature of the middle (i.e.,second) plate under steady-state condition is

For a perfect black body,the absorption coefficient is