Physics Talk

Zouavman Le Zouave / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0); https://commons.wikimedia.org/wiki/File:Light_shining1.JPG The Rayleigh-Jeans law, based on classical physics, gives the spectral radiance (linked to intensity) of blackbody electromagnetic radiation as a function of wavelength: B v (T) is spectral radiance; k B is the Boltzmann constant; T is temperature; c is the speed of light; λ is wavelength. [1] Blackbodies are defined as ‘[idealised] objects that perfectly absorb and then re-emit radiation’ [2] . The equation shows that increasing the wavelength should cause the spectral radiance of the emitted radiation to decrease and tend to zero whilst decreasing wavelength causes it to increase, tending to infinity. This graph [3] shows what the Rayleigh-Jeans law predicts (labelled ‘Classical theory’) and what actually happens at different temperatures (the blue, green and red lines). Although the law seems to coincide with exper