That it can absorb and emit freely at all wavelengths.Kqwert said:what really differs a black body and a non-black body in this case?
Alright, but the attribute of emitting all absorbed radiation is not unique for black bodies, rather it holds for all bodies?haruspex said:That it can absorb and emit freely at all wavelengths.
That it can emit at all the wavelengths at which it absorbs, yes, but that is not quite what you wrote.Kqwert said:Alright, but the attribute of emitting all absorbed radiation is not unique for black bodies, rather it holds for all bodies?
Kirchoff's Law, also known as Kirchoff's Radiation Law, is a fundamental principle in physics that describes the relationship between the emission and absorption of thermal radiation by a material or object. It states that the ratio of emissive power to absorptive power of a material at a given temperature is equal to the ratio of its emissivity to its absorptivity.
Kirchoff's Law is a key component of the theory of blackbody radiation, which states that a perfect blackbody, which absorbs all incident radiation, also emits radiation at a maximum rate for a given temperature. This is described by the blackbody curve, which is based on Kirchoff's Law.
In thermodynamics, Kirchoff's Law is significant because it helps to explain the behavior of thermal radiation in systems such as engines and heat transfer processes. It is also used in the calculation of thermodynamic properties, such as the emissivity and absorptivity of materials.
While Kirchoff's Law was originally formulated for thermal radiation, it can also be applied to non-thermal radiation, such as electromagnetic radiation. In this case, the ratio of emissive power to absorptive power is equal to the ratio of the material's reflectivity to its transmissivity.
Kirchoff's Law differs from other laws of radiation, such as Stefan-Boltzmann Law and Wien's Displacement Law, in that it is a general principle that can be applied to all types of radiation. It does not provide specific equations or formulas, but rather a fundamental understanding of the relationship between emission and absorption of radiation by materials.