Heat is a form of energy that is transferred from one body (system
) to another body (system or surroundings). Heat transfer can occur when there is a
temperature difference. Assume two bodies with different temperatures are brought into contact with each other.
The heat transfers from the hotter body to the colder one. This will continue until the temperature of the bodies are the same (thermal equilibrium).
The SI unit of heat is joule (J). Other units are: