# Stefan's law

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## Stefan's law

(ˈstɛfənz)
n
(General Physics) the principle that the energy radiated per second by unit area of a black body at thermodynamic temperature T is directly proportional to T4. The constant of proportionality is the Stefan constant, equal to 5.670400 × 10–8 Wm–2 K–4. Also called: Stefan-Boltzmann law
[C19: named after Josef Stefan (1835–93), Austrian physicist]
References in periodicals archive ?
Among the experiments themselves are to determine the wavelength of monochromatic light (sodium light) by Newton's ring, to determine the specific rotation of cane sugar solutions using half-shade polarimeter, to verify Stefan's Law by electric method using a vacuum diode, to determine the energy band gap of a given extrinsic semi-conductor material by thermal variation using a four probe method, and to determine the coefficient of viscosity of a water by Meyer's disc method.
The outer cavity has a perfect emissivity ([member of] = 1) and is able to pump out additional photons, as required by Stefan's law .
We have the famous Newton's laws of motion, Heisenberg's uncertainty principle, Stefan's law, Bragg's law, Hund's rule, Mossbauer effect to name but a few.
He studied hot bodies over a considerable range of temperature and, in 1879, was able to show that the total radiation of a body was proportional to the fourth power of its absolute temperature (Stefan's law).
In 1898, Scheiner brought apparent unification to the problem when he applied Stefan's law  to data acquired by Pouillet, Secchi, Violle, Soret, Langley, Wilson, Gray, Paschen, and Rosetti .
Through this letter, I wish to highlight that the modeling of the Earth's energy balance [5,6] requires re-evaluation first of Kirchhoff's law of thermal emission [7-11] and its associated consequences for the application of Stefan's law , and second of the assignment of the microwave background [13,14] to the oceans of the Earth [15,16].
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