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 per second at temperature $T.$

• A. $0.6\sigma {AT}^4$
• B. $0.4\sigma {AT}^4$
• C. $0.8\sigma {AT}^4$
• D. $1.0\sigma {AT}^4$

Answer 1

The correct option is D $1.0\sigma {AT}^4$

When a non black body is placed inside a hollow enclosure the total radiation from the body is the sum of what$.$

It would emit in the open with $(e<1)$ and the part $(1-a)$ of the incident radiation from the walls reflected by it$.$

the two add up to a black body radiation$.$

So$,$ the totall radiation emitted by the body is $1.0\sigma A{T}^4$

Hence,

option $\left(D\right)$ is correct answer.