Kirchhoff's Law Kirchhoff's law states that the total heat energy flow into a closed surface is equal to the total heat energy flow out of the surface. This...
Kirchhoff's Law
Kirchhoff's law states that the total heat energy flow into a closed surface is equal to the total heat energy flow out of the surface. This means that there is no net change in thermal energy within the surface.
Explanation:
Kirchhoff's law can be understood intuitively by considering that heat energy must flow from hotter to colder regions of a surface. If you imagine a hot pan placed on a cold surface, heat will flow from the pan to the surface until the pan and the surface reach the same temperature. According to Kirchhoff's law, this means that the surface will eventually reach the same temperature as the pan, regardless of its initial temperature.
Examples:
When sunlight is incident on a metal surface, heat is transferred from the metal to the air. This causes the surface to become hot. According to Kirchhoff's law, the air will eventually reach the same temperature as the surface.
When a hot stove is placed on a cold floor, heat is transferred from the stove to the floor. This causes the floor to become warm. According to Kirchhoff's law, the stove will eventually reach the same temperature as the floor