A spherical ball A of surface area `20cm^(2)` is kept at the centre of a hollow spherical shell B of area `80cm^(2)` . The surface of A and the inner surface of B emit as blackbodies. Both A and B are at 300K. (a) How much is the radiation energy emitted per second by the ball A? (b) How much is the radiation energy emitted per second by the inner surface of B? (c) How much of the energy emitted by the inner surface of B falls back on this surface itself?

Answer

A, B, C, D

Explanation

`A_(A)=20 cm^(3), A_(B)=80 cm^(2)`
`(rms)_(A)=42 J, ^(@)C, (rms)_(B)=82 J/^(@)C`