14.1.2—Regions of equal temperature are in thermal equilibrium
- Syllabus
- 9702–2028–2029
- Objective
- 14.1.2
- Level
- A2
Thermal equilibrium means regions have equal temperature and no net heat transfer
Two systems are in thermal equilibrium when their temperatures are equal, so there is no net transfer of thermal energy between them in contact.
Microscopic exchanges may still occur, but they balance on average. Thermal equilibrium is not the same as identical internal energy.
A thermometer left long enough in a liquid reaches the liquid’s temperature and is then in thermal equilibrium with it.
Equal temperature does not mean equal mass, energy content or particle number.
ConceptA-Level CAIE Physics A2