Question

Two identical objects A and B (emissivity $e_A$ and $e_B$ ;$e_A\ne e_B$) are placed in an enclosure. Temperature of body A, B and enclosure are same and constant.

• A. heat emitted by body 'A' is not equal to heat emitted by body B.
• B. heat absorbed by body 'A' is not equal to heat absorbed by body B.
  
• C. If $e_A>e_B$, body A absorbs more heat than body B
  
• D. If $e_A<e_B$, body A emits less heat than body B.

Answer 1

The correct option is D If $e_A<e_B$, body A emits less heat than body B.

Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a blackbody at the same temperature and wavelength and under the same viewing conditions.
So, if $e_A<e_B$, body A emits less heat than body B.