Photon picture of em radiations :
(i). In interaction of radiation with matter, radiation behaves as if it is made of particles like photons.
(ii). Each photon has energy E(= h) and momentum p (=\(\frac{h}{\lambda}\))
(iii). Irrespective of the intensity of radiation, all the photons of a particular frequency and wavelength have the same energy and same momentum.
(iv). Photon energy is independent of the intensity of radiations.
(v). Photons emitted from a source of radiations travel with the speed of light.
(vi). The rest mass of a photon is zero.
(vii). Photons are electrically neutral
(viii). In a photon particle collision, the energy and momentum are conserved.
However,
Number of photons may not be conserved, photon may be absorbed or new photon may be created.
