Heat Radiation

Written by Jerry Ratzlaff. Posted in Thermodynamics

Heat radiation (one of three ways to heat transfer: conduction, convection and radiation) is the flow of energy through electromagnetic waves such as infrared, light, microwaves, etc.


\(Q =   \epsilon \sigma A  \Delta T^4     \)

\(Q =   e \sigma  A  \left(  T_o \;-\; T_e  \right)^4     \)


\(Q\) or \(\phi\) (Greek symbol phi) = heat radiation or transfer

\(\epsilon\) (Greek symbol epsilon) = the emissivity of the particular body and is a number between 0 and 1

\(\sigma\) (Greek symbol sigma) = Stefan-Boltzmann constant

\(A\) = cross sectional area  

\(\Delta T\) = temperature differential

\(T_o\) = absolute temperature of the object emitting

\(T_e\) = absolute temperature of the environment