What is Stefan–Boltzmann law?
{{unreferenced|date=July 2012}} In [[quantum physics]], the '''Stefan-Boltzmann law''' (sometimes called '''Stefan's Law''') states that the [[black-body radiation]] energy emitted by a given object is directly [[Proportionality|proportional]] to the [[temperature]] of the object raised to the [[fourth power]]. The [[equation]] for this law is: R=σ''T''<sup>4</sup> where σ is the '''Stefan-Boltzmann constant''', which is equal to 5.670 373(21) x 10<sup>-8</sup> W m<sup>-2</sup> K<sup>-4</sup>, and where R is the energy radiated per unit surface area and per unit time. ''T'' is temperature, which is measured in [[Kelvin]] scale. Although this law is accurate and helpful, it is only usable for the energy radiated by blackbodies. {{physics-stub}} [[Category:Laws of physics]]