A surface at temperature `T_(0)K` receives power `P` by radiation from a small sphere at temperature `T ltT_(0)` and at a distance d. If both `T` and d are doubled the power received by the surface will become .

Options

A. `P`
B. ` 2 P`
C. `4 P`
D. `16 P`

Answer

C

Explanation

power `PpropT^(4)andPprop(1)/(d^(2))` , therefore,
`Pprop(T^(4))/(d^(2))prop(2^(4))/(2^(2))=2^(2)=4` times i.e .4 P