Main Features of Photons:
Electromagnetic radiations (like light waves, radio waves etc.) carry energy in packets or bundles known as Photons or Quanta. The main features of Photons are as under-
1:- Photons travel in a straight line.
2:- The energy of the Photon is given by-
| E = hν = hc/λ |
Where ‘h’ is Planck’s constant and its value is 6.62 x 10-34 Js, ‘ν’ is the frequency of Photon, ‘λ’ is the wavelength of Photon and ‘C’ is the velocity of light.
3:- All Photons travel in space with the same speed (equal to the speed of light).
4:- Photons are electrically neutral.
5:- The energy of the Photon is usually expressed in electron-volt where-
| 1ev = 1.6 x 10-19 J |
6:- Photons are not deflected by electric and magnetic fields.
7:- The momentum of the Photon is given by-
| mc = h/λ |
8:- The mass of the Photon is given by-
| m = h/cλ |
9:- From the theory of relativity-
| m = m0/√[1 – (ν’2/c2)] |
Where m0 is the rest mass of the particle.
| ∴ m0 = m √[1 – (ν’2/c2)] In case of Photon, ν’ ≈ C ⇒ m0 = 0 |
Hence Photon has zero rest mass. Hence, Photon cannot exist at rest.
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