Question

Considered a black body radiation in a cubical box at absolute temperature t if the length of each side of the box is doubled and the temperature of the walls of the box and that of the radiation is halved then the total energy​

Answer 1

The total energy will remain the same.

Solution :

• We are given a black body kept in a cubical box with the absolute temperature as t.
• Now, the length of each side of the box in doubled and the temperature of the walls as well as that of the radiation is halved.
• Hence, the temperature now will be T/2 .
• Here we can observe that the temperature of the body and that of the surroundings remain same in both cases.
• This shows that there is no net loss of radiation occurring through the body.  
• That is why, the total energy remains constant.