Kirchoff's Law of Thermal Radiation

Kirchhoff's Law of Thermal Radiation states that a material’s ability to emit thermal radiation is equal to its ability to absorb it at the same temperature and wavelength. In simple terms, a perfect absorber (called a blackbody) emits the maximum possible radiation at a given temperature, and a perfect emitter at that temperature can absorb all incident radiation without exception. This relationship explains why objects in thermal equilibrium emit and absorb radiation equally, and it helps us understand how different materials radiate heat energy based on their properties and temperature.