Two identical objects A and B (emissivity $e_{A}$ and $e_{B}; e_{A} \neq = e_{B}$ ) are placed in an enclosure. Temperature of body A, B and enclosure are same and constant :-

Question

Two identical objects A and B (emissivity e A ​ and e B ​ ; e A ​  = e B ​ ) are placed in an enclosure. Temperature of body A, B and enclosure are same and constant :-

TestHub · Accepted Answer

Let S be the common surface area and T the common constant temperature. For each body in thermal equilibrium:

$P_{emitted} = P_{absorbed} = e σ S T^{4}$

The two bodies therefore have different emitted and absorbed powers because their emissivities differ.

$\frac{P _{A}}{P _{B}} = \frac{e _{A}}{e _{B}}$

If eA > eB, A absorbs more. If eA < eB, A emits less. All four statements are correct. Net heat exchange is zero for each body.

Physics - Heat & Thermo Question with Solution | TestHub

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