The rate of dissipation of heat by a black body at temperature `T` is `Q`. What will be the the rate of dissipation of heat by another body at temperature `2T` and emissivity `0.25`?

Options

A. 16 Q
B. 4Q
C. 8Q
D. 4.5Q

Answer

B

Explanation

By Stefan's law
`Q=sigmaT^(4)`
The rate of dissipation of heat by a body emissitivity e is given by
`Q'=e sigmaT`^('4)`
Here `T'=2T and e=0.25`
`Q'=0.25xxsigma(2T)^(4)`
`Q'=4sigmaT^(4)=4Q`