Second, the emissive power is a direct measure of the total radiation emitted by an object.
However, energy is emitted by an ideal radiator over a range of wavelengths, and at any given
temperature the distribution of the energy emitted as a function of wavelength is unique. Max Planck
(1858–1947) developed the basis for the theory of quantum mechanics in 1900 as a result of
examining the wavelength distribution of radiation. He proposed the following equation to describe
the wavelength distribution of thermal radiation for an ideal or blackbody radiator: