Question

A spherical body of area a and emissivity e = 0.6 is kept inside a black body what is the rate at which energy is radiated

Answer 1

1.0eAT ^ 4

If a non-black body is placed inside a void enclosure, then the overall radiation from the body is would be the sum of what it would emitted in the open (e <1) and the part (1-a)  of the incident radiation from the reflecting walls through this. this both add a black body radiation. Therefore, the total rate of radiation emitted by the body is 1.0σAT^4.