This Demonstration plots the radiated heat from a gray body having a given emissivity as a function of its temperature and that of its surroundings using the Stefan–Boltzmann law.
Snapshot 1: domestic fireplace radiation
Snapshot 2: industrial smelter radiation
Snapshot 3: sun-like stellar radiation
This Demonstration plots the radiated heat in or from a hot body having a given emissivity, , as a function of its temperature and that of its surroundings, both entered either in °C or °K. This heat output is calculated with the Stefan-Boltzmann law, , where is the emissivity, is the Stefan-Boltzmann constant, is the area in (equal to 1 in this Demonstration), is the radiating body temperature, and is the ambient temperature, both in °K. The upper graphic is a schematic visual representation of the selected emissivity (not to scale).