Radiant energy

Radiant energy is a photometric quantity that quantifies the amount of energy emitted by a source. Included in this energy is radiation at all wavelengths. The unit is Joule [J]. In the case of electromagnetic radiation in the region of the visible spectrum, the radiant energy is the sum of the energies of all photons in wavelengths visible to the naked eye. If we limit ourselves to radiation in the visible part of the spectrum, we are talking about light energy.