photon The quantum of electromagnetic radiation. The electromagnetic waves have dual nature, the wave and the particle. The particles of electromagnetic radiation are called photons. If n is the frequency of the electromagnetic waves , then each photon has energy equal to hn , where h is the Planck’s constant. The momentum of the photon is hn /c. The photons can be scattered like particles. The rest mass of photon is zero, and its spin 1. They obey Bose Einstein statistics.