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Modern Physics
Modern Physics

Photon Momentum

p=hλ=Ecp = \frac{h}{\lambda} = \frac{E}{c}

Photons carry momentum despite having no rest mass. This is key to understanding radiation pressure and Compton scattering.

Variables

p
Photon momentum
kg·m/s
h
Planck constant
J·s
\lambda
Wavelength
m
E
Photon energy
J
c
Speed of light
m/s

Derivation

From E = pc for massless particles and E = hc/λ for photons.

Your notes

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Common questions

What is the Photon Momentum formula?

Photon Momentum is written p = h/λ= E/c. Photons carry momentum despite having no rest mass. This is key to understanding radiation pressure and Compton scattering. It belongs to Modern Physics, under Quantum Mechanics.

What are the units in p = h/λ= E/c?

In SI units, p is photon momentum, measured in kg·m/s; h is planck constant, measured in J·s; \lambda is wavelength, measured in m; E is photon energy, measured in J; c is speed of light, measured in m/s.

How is the Photon Momentum formula derived?

From E = pc for massless particles and E = hc/λ for photons. The result is p = h/λ= E/c.