# What is the Planck’s law?

As mentioned in FAQ section, the quantity of energy emitted by a true blackbody only depends on its temperature. This radiation level, named Radiant Emittance R, is defined by the following distribution discovered in 1900 by the German scientist, Max Planck:

Where:

- h is the Planck’s constant, h=6.626 x 10
^{34}Js - K is the Boltzmann’s constant, K=1.381 x 10
^{-23}J/K - c is the speed of light, c=2.998 x 10
^{8}m/s - λ is the wavelength (in meters)
- T is the temperature of the blackbody in Kelvin: T (Kelvin) = 273,16 + t (Celsius degree).

Download our calculation sheet to determine the energy emitted by a true blackbody at selected wavelengths, depending on the temperature of the blackbody.