Answer: photons

AnswerCrossword Clue
PHOTONSParticles in physics
PHOTONSLight quanta
PHOTONSRadiation particles
PHOTONSElectromagnetic energy units
PHOTONSLight intensity units
photonsA particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass
photonsPHOTON, an elementary particle