Elektromagnetiline kiirgus, nähtus, mille olemust ei tunta, seda defineeritakse enamasti tema omaduste või teiste definitsioonide kaudu
on elektromagnetiline kiirgus on:
… energia, mis vabaneb teatud ekektromagetiliste protsesside käigus
In radiometry, radiant energy is the energy of electromagnetic radiation. The SI unit of radiant energy is the joule (J). The quantity of radiant energy may be calculated by integrating radiant flux (or power) with respect to time. http://en.wikipedia.org/wiki/Radiant_energy
Electromagnetic radiation, in terms of classical theory, the flow of energy at the universal speed of light through free space or through a material medium in the form of the electric and magnetic fields that make up electromagnetic waves such as radio waves, visible light, and gamma rays. http://www.britannica.com/EBchecked/topic/183228/electromagnetic-radiation