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Momentum of Photon

Photon is a type of elementary particle which has a zero rest mass and moves with a speed of light in the vacuum. Einstein explained the momentum (p) of a photon with the given formula. The energy and momentum of a photon are related by the equation

E = pc

where,

E = energy of the photon

p = momentum of the photon

c = speed of light

The momentum of Photon in terms of wavelength is given by the following derivation

p = mc——–(1)

The energy (E) of a photon is given as

E = mc²,

E = hν (frequency,ν=c/λ)

Therefore,

E = hc/λ

hc/λ=mc²

m =h/λc————-(2)

substituting equation (2) in equation (1) we get

E = photon energy

h= Planck’s constant(6.62607015×10⁻³⁴ Js)

λ = wavelength of light

Photon momentum is comparatively small value to measure.

An electron with the same momentum has a 1460 m/s velocity, which is non-relativistic.