Svartkroppsstrålning

Svartkroppsstrålning refers to the electromagnetic radiation emitted by a body that is a perfect absorber and emitter of radiation at all frequencies. This idealized object, known as a blackbody, absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence, and therefore appears "black" at room temperature. When heated, a blackbody emits radiation. The intensity and spectral distribution of this emitted radiation are solely dependent on the temperature of the blackbody.

The study of blackbody radiation was crucial in the development of quantum mechanics. Classical physics failed to accurately describe the observed spectrum of blackbody radiation, particularly at shorter wavelengths, a phenomenon known as the ultraviolet catastrophe. Max Planck proposed a revolutionary solution in 1900 by postulating that energy is not emitted or absorbed continuously, but rather in discrete packets called quanta. The energy of these quanta is directly proportional to the frequency of the radiation.

Planck's law describes the spectral radiance of blackbody radiation as a function of frequency and temperature. It accurately predicts the observed spectrum across all wavelengths, from the peak emission at a certain frequency to the tails at both lower and higher frequencies. As the temperature of the blackbody increases, the total emitted energy increases, and the peak of the spectral distribution shifts towards shorter wavelengths, meaning it emits more visible light and even ultraviolet radiation at higher temperatures. This is why objects glow red, then orange, then yellow, and eventually white-hot as they are heated.