StefanBoltzmannovým

The Stefan-Boltzmann law, also known as the Stefan law, is a physical law that describes the total energy radiated by a black body in terms of its temperature. Specifically, it states that the total energy radiated per unit surface area of a black body across all wavelengths is directly proportional to the fourth power of the black body's absolute temperature. The constant of proportionality is known as the Stefan-Boltzmann constant, denoted by the Greek letter sigma ($\sigma$). The law can be expressed mathematically as $P/A = \sigma T^4$, where $P$ is the power radiated, $A$ is the surface area, and $T$ is the absolute temperature in Kelvin.

The Stefan-Boltzmann constant, $\sigma$, has a value of approximately $5.670374419 \times 10^{-8} \text{ W m}^{-2} \text{ K}^{-4}$. This law is fundamental in thermodynamics and astrophysics, used to calculate the energy radiated by stars, estimate their surface temperatures, and understand the behavior of thermal radiation. It was first formulated by the Slovenian physicist Josef Stefan in 1879 and later derived theoretically by the Austrian physicist Ludwig Boltzmann in 1884. The law applies ideally to black bodies, which are perfect absorbers and emitters of radiation. Real objects are often approximated as gray bodies, with emissivities less than one.