Stefan–Boltzmann Law

The equation shown in the image is the Stefan-Boltzmann law. “P” is the power radiated by the ideal radiator, and ‘σ‘is the Stefan-Boltzmann constant, which has the value

σ = 5.67*10^-8 Wm^-2K^-4

Where ‘P’ is in Watts, emissivity (e) has no units, Area (A) m² and Temperature (T) is in Kelvin.

In the thermodynamic analysis, the energy density is related to a square per unit of time and per unit area. Thus, the heat interior surface of an enclosure produces a specific energy density of thermal radiation. We are interested in radiant exchange with surfaces – hence the reason for the expression of radiation from a surface in terms of its temperature.

Applications:

The Stefan–Boltzmann Law is widely used in physics and engineering to:

• Calculate the radiant energy output of stars and planets.
• Estimate the cooling rates of objects through thermal radiation.
• Determine temperatures based on observed thermal emissions, such as in thermal imaging and climate science.