Question

Two identical objects $A$ and $B$ are at temperatures $T_A$ and $T_B$. respectively. Both objects are placed in a room with perfectly absorbing walls maintained at a temperature $T$ ($T_A$ > $T$> $T_B$). The objects $A$ and $B$ attain the temperature $T$ eventually. Select the correct statements from the following

• A. $A$ only emits radiation, while $B$ only absorbs it until both attain the temperature $T$
• B. $A$ loses more heat by radiation than it absorbs, while $B$ absorbs more radiation than it emits until they attain the temperature $T$
• C. Both $A$ and $B$ only absorb radiation, but do not emit it, until they attain the temperature $T$
• D. Each object continues to emit and absorb radiation even after attaining the temperature $T$

Answer 1

Answer: (B)

$A$ loses more heat by radiation than it absorbs, while $B$ absorbs more radiation than it emits until they attain the temperature $T$

1.Since the temperature of $A$ is higher than the temperature of the surrounding hence $A$ radiates heat much larger than it absorbs heat. Since the temperature of $B$ is lower than the temperature of the surrounding hence $B$ absorbs heat much larger than it radiates.
This process goes on until both $A$ and $B$ reach the temperature $T$.
2.Even after reaching thermal equilibrium, both bodies keep radiating and absorbing.
Hence ,options $B$ and $D$ are correct.