Question

For two bodies to be in thermal equilibrium, they must be separated by:

• A. An adiabatic wall
• B. A diathermic wall
• C. Both A and B
• D. None of the above

Answer 1

The correct option is B A diathermic wall

If two systems are seperated by a wall permeable to heat transfer i.e a diathermic wall, both systems will undergo heat transfer with each other and once the steady state is reached, they will come into thermal equilibrium. Suppose, the systems are seperated by an adiabatic wall. Then, energy transfer cannot happen in the form of heat. Thus, the systems will never come into thermal equilibrium with each other without the aid of any other system as a mediator.
Thus, option (b) is the correct answer.