#### CHAPTER 11 DUAL NATURE OF RADIATION AND MATTER

Photon

Photons are the packets of energy emitted by a source of radiation. The energy of each photon is,

E = hν,

where h is Planck’s constant and ν is frequency of radiation.

The rest mass of a photon is zero.

The momentum of a photon

Dynamic or kinetic mass of photon,

where c is speed of light in vacuum and λ is wavelength of radiation.

Photons are electrically neutral.

A body can radiate or absorb energy in whole number multiples of a quantum, that is hν, 2hν, 3hν …, nhν, where n is positive integer.