Photons:- Electromagnetic radiation carry energy in the form of packets or bundles known as photons or quanta.

Properties of Photons:-

1. A photon is a packet or bundle of energy & the energy associated with a photon is given by

E = h

h --> Plank’s constant = 6.625 x 10^-35 Js.

ν --> Frequency of Photon.

As           ν = c/ λ

So           E = hc/ λ

2. A photon travels at a speed of light in vacuum (3 x 10⁸ m/s)
3. A photon has zero rest mass i.e. mo = O. It means that a photon cannot exist at rest.

Mass of a particle moving with velocity ν is given by:-

if v = c then m_o = 0.

d.The kinetic mass of a proton is m = E/c² =hν/c² = h/cλ

e.The momentum of a photon is p = E/c = hν/c = h/λ

f. Photons always travel in a straight line.

g. Wavelength of the photon charges in different media so velocity of photon is different in different media.

h. Photons do not have charge so they are electrically neutral.

Photon are not deviated by magnetic as well as electrical field.