|SI||5.670 374 419 ...e-8th|
|Relation to other constants|
: Boltzmann constant : Planck's quantum of action : speed of light
|Sources and Notes|
|Source SI value: CODATA 2018 ( direct link )|
The Stefan-Boltzmann constant , after Josef Stefan and Ludwig Boltzmann , not to be confused with the Boltzmann constant , is a physical constant that occurs as a proportionality constant in the Stefan-Boltzmann law . According to this, the power of a black body emitted in the form of electromagnetic radiation is proportional to its surface area and the fourth power of its temperature :
The constants k B ( Boltzmann constant ), h ( Planck's quantum of action ) and c ( speed of light ) are used in the SI system to define the units of measurement and are assigned exact numerical values. This means that the Stefan-Boltzmann constant also has an exact value in the SI.
- The value of the Stefan-Boltzmann constant in SI units is exact , i.e. H. without measurement uncertainty, but due to the factor π 5 it has no finite representation of decimal places.