The rectangular surface of area `8 cm xx 4 cm` of a black body at temperature `127^(@)C` emits energy `E` per section if length and breadth are reduced to half of the initial value and the temperature is raised to `327^(@)C`, the ratio of emission of energy becomes

Options

A. `(3)/(8)E`
B. `(81)/(16)E`
C. `(9)/(16)E`
D. `(81)/(64)E`

Answer

D

Explanation

`E=sigma xx "area" xx T^(4)`, T increases by a factor `(3)/(2)`.
Area increases by factor `(1)/(4)`.