Stefan-Boltzmann Gesetz

For a black body

Heat flux: ${\dot{q}}_s=\sigma \cdot T^4$

Stefan-Boltzmann constant:
$\sigma =5.6704\cdot 10^{-8}W/m^2{K}^4$

${\dot{q}}_s$: Wärmestromdichte
T in Kelvin

For grey body

Heat flux: ${\dot{q}}_s=\epsilon \cdot \sigma \cdot T^4$

$\epsilon$: emission coefficient ($0<\epsilon <1$)

Zwischen zwei Körpern

$\dot{q}=\sigma \cdot F_{12}\cdot (T_1^4-T_2^4)$

$F_{12}$: the radiation properties of both bodys
- ${\epsilon }_1$ and ${\epsilon }_2$
- relative orientation to each other