# Do Waves have mass? [duplicate]

Do any form of electromagnetic waves like visible light have mass? It is known that all electromagnetic waves have energy. According to Einstein's

$$E^2=p^2c^2 + m^2c^4$$

formula, the energy of a particle like photon, which shows wave properties as well, is derived from its mass and momentum. Some suggest that photons are indeed mass-less and that photons have energy due to there momentum, but momentum itself is equal to mass times velocity, $p=mv$.Then how can a body have momentum and not mass? The experiment on photoelectric effect by Einstein clearly proves Planck's theory of energy packets(photons) as correct, thus providing concrete evidence for the wave-particle duality of photons. Could anyone provide an explanation that is understandable to interested high-school students? Thank you:)