Chapter 12, Problem 12.84P

Consider the diffuse, gray opaque disk $A_1$ , which has a diameter of 10 mm, an emissivity of 0.3, and is at a temperature of 400 K. Coaxial to the disk $A_1$ , there is a black, ring-shaped disk $A_2$ at 1000K having the dimensions shown in the sketch. The backside of $A_2$ is insulated and does not directly irradiate the cryogenically cooled detector disk $A_3$ , which is of diameter 10 mm and is located 2 m from $A_1$

Calculate the rate at which radiation is incident on $A_3$ due to emission and reflection from $A_1$ .