The Stefan–Boltzmann law, also known as Stefan's law, describes the intensity of the thermal radiation emitted … See more

The radiant exitance (previously called radiant emittance), , has dimensions of energy flux (energy per unit time per unit area), and the SI units of measure are joules per second per square metre (J⋅s ⋅m ), or equivalently, … See more

In 1864, John Tyndall presented measurements of the infrared emission by a platinum filament and the corresponding color of the filament. The proportionality to the fourth power of the absolute temperatur… See more

The Stefan–Boltzmann constant, σ, is derived from other known physical constants: where k is the Boltzmann constant, the h is the Planck constant, and c is the speed of light in vacuum.
As of the … See more

With his law, Stefan also determined the temperature of the Sun's surface. He inferred from the data of Jacques-Louis Soret (1827–1890) that the energy flux density from the Sun is 29 times greater than the en… See more

The fact that the energy density of the box containing radiation is proportional to can be derived using thermodynamics. This derivation uses the relation between the radiation pressure p and the internal energy density , … See more