Stefan-Boltzmann constant
The
Stefan-Boltzmann constant (also
Stefan's constant), denoted with a Greek letter σ, is a derivable
physical constant, the
constant of proportionality between the total
energy radiated per unit surface area of a
blackbody in unit time and the fourth power of the
thermodynamic temperature, as per the
Stefan-Boltzmann law.
Its value is 5.670 400(40) × 10-8 J s-1 m-2 K-4.
The Stefan-Boltzmann constant can be defined in terms of the Boltzmann constant k by
where
h is
Planck's constant,
ħ is
h-bar, and
c is the
speed of light.