According to Teach Astronomy, the Stefan-Boltzmann Law can be applied to a star's size in relation to its temperature and luminosity. It can also apply to any object emitting a thermal spectrum, including metal burners on electric stoves and filaments in light bulbs.
According to Hyper Physics, the Stefan-Boltzmann Law states that the thermal energy radiated by a blackbody radiator per second per unit area is proportional to the fourth power of the absolute temperature. The law is also related to the energy density in the radiation in a given volume of space.
According to Teach Astronomy, the mathematical form of the Stefan-Boltzmann Law states that the luminosity of a star is proportional to the star's surface area and the fourth power of its surface temperature. Therefore, changing the temperature or radius of a star changes the amount of energy radiated, or luminosity. This is why hotter stars radiate bluer light and more light per unit area at every wavelength than cooler stars. The law is used to calculate the radii of stars. The Stefan-Boltzmann Law can also be seen in everyday occurrences. For example, when an iron poker is heated, it goes from glowing red to glowing yellow as the temperature rises.