Consider the diffuse, gray opaque disk A1, which has a diameter of 10 mm, an emissivity of 0.3, and is at a temperature of 400 K. Coaxial to the disk A1, there is a black, ring-shaped disk A2 at 1000 K having the dimensions shown in the sketch. The backside of A2 is insulated and does not directly irradiate the cryogenically cooled detector disk A3, which is of diameter 10 mm and is located 2 m from A1, Calculate the rate at which radiation is incident on A3 due to emission and reflection from A1.

A2 L: Ar- 10 mm = 500 mm Radiation detector, A3 A -Insulation Im lm