Question

Heat always flows from higher temperature to lower temperature.
A. True
B. False

Answer 1

Hint: Define temperature of a system. The second law of thermodynamics tells us that the entropy of a closed system will always tend to increase. Use this concept to give the answer to the above question.

Complete step by step answer:
If we have a temperature difference between two systems which are in constant contact with each other, the heat will always transfer from one system to another until both the systems are in thermal equilibrium with each other.
From the second law of thermodynamics, we know that the entropy of a closed system can never decrease. So, from this law we get that heat will always flow from a state of higher temperature to a state of lower temperature. Heat is a form of energy. The atoms of the system with higher temperature will gain the heat energy and the vibration of these atoms will increase. The atoms or molecules on the system with lower temperature have lower temperature and are not vibrating. So, the vibrating atoms of the system with higher temperature will collide with the atoms or molecules of the system with lower temperature and transfer the energy gained from the hot system. This way the energy of the atoms or molecules in the system with lower temperature will increase and this energy will eventually be released in the system and the temperature of the system will increase. So, we can say that heat always flows from higher temperature to a lower temperature.

So, the correct answer is “Option A”.

Note:
A lower entropy state is highly ordered and a higher entropy state is highly disordered. The system with higher temperature has high entropy while the system with lower temperature has lower entropy. As the heat transfers from the hot end to the cold end equilibrium is reached. At this point the entropy of the whole system has spontaneously increased.