Thermal equilibrium simple explanation

Added: 2026-05-01

[00:00:01]Now the question arises, what is exactly thermal equilibrium?

[00:00:06]Whenever two bodies are at the different temperatures, heat flow from hotter body to the colder one.

[00:00:12]This process continues until both bodies reach the same temperature. At this point, the system is said to be in thermal equilibrium.

[00:00:21]Even though microscopic energy exchanges may still occur, there is no observable heat transfer at macroscopic level.

[00:00:30]It is also important to note that two objects at the same temperature can contain different amounts of heat, depending on their mass and the material they are made of.

[00:00:41]Thermal equilibrium is a fundamental concept in thermodynamics and forms the basis of the temperature measurement.

[00:00:48]A thermometer works by coming into thermal equilibrium with the object being measured.

[00:00:55]Only after this equilibrium is reached, it shows the correct temperature.

[00:01:00]This idea is closely related to the zeroth law of thermodynamics.

[00:01:05]Zeroth law states that if two bodies are each in thermal equilibrium with a third body, they are also in thermal equilibrium with each other.

[00:01:17]This law provides the foundation for defining the temperature and ensures the consistency in how we measure it.

[00:01:26]And that is the core idea of heat, temperature, and thermal equilibrium.