AT4 where E is the energy emitted by an
object of area A with temperature T. is a constant. Radiation Laws and Stellar Behavior
We learned the Stefan-Boltzmann Law:
the total energy emitted by a blackbody E = AT4 where E is the energy emitted by an
object of area A with temperature T. is a constant.
We can combine this law with the inverse r square law, the brightness of a light source is inversely proportional to the square of the source’s distance from us:
where F = number of photons produced by the source and r = object’s distance.
For example, if we know the temperature of a star, its brightness, and its distance, we can determine its size. For example, if we guess a size in the Stefan-Boltzmann Law, then the inverse r squared law will predict a brightness. If that is not what we measure, we can adjust the size until we get agreement.