What is the first law of radiation?

Kirchhoff's law of thermal radiation. In heat transfer, Kirchhoff's law of thermal radiation refers to wavelength-specific radiative emission and absorption by a material body in thermodynamic equilibrium, including radiative exchange equilibrium. A body at temperature T radiates electromagnetic energy.

Answer:The first law of thermal radiation states that each square meter of a hotter object's surface emits more light at all wavelengths. What this means is that if you compare two objects that are giving off heat, and one object is hotter than the other, each square meter of the surface of that object emits more light than the cooler object at every wavelength of light.