Thermal Equilibrium

In physics, thermal equilibrium is a state in which two systems (or bodies) are in thermal contact with each other and there is no net flow of heat between them. The system is said to be "in equilibrium" when its properties do not change over time.

Conditions for Thermal Equilibrium

In order for thermal equilibrium to occur, the following must hold true:

1. Both systems must be at the same temperature. This means that they have the same average kinetic energy of their particles.
2. There can be no net flow of heat between the two systems. If there is a flow of heat, then one system will become warmer while the other becomes cooler until they reach the same temperature.

If both of these conditions are met, then the two systems are in thermal equilibrium with each other.

Examples of Thermal Equilibrium

• Hot object in a room: When a hot object is placed in a room that is at the same temperature as the object, the heat will flow from the hot object to the cooler surroundings until both the object and the room reach the same temperature. At this point, there is no net flow of heat and they are said to be in thermal equilibrium.
• Hand on a table: When two objects are placed in contact with each other and there is no net flow of heat between them. For instance, if you place your hand on a table, your hand will eventually reach the same temperature as the table. Once again, there is no net flow of heat and they are in thermal equilibrium.