Photon momentum

Definition

Photon momentum is the momentum carried by a photon, despite it having no mass. It is given by $p = \frac{h}{\lambda}$, where $p$ is the momentum, $h$ is Planck's constant, and $\lambda$ is the wavelength of the photon.

5 Must Know Facts For Your Next Test

1. Photon momentum is derived from the Planck-Einstein relation and De Broglie's hypothesis.
2. The formula for photon momentum is $p = \frac{E}{c}$, where $E$ is the energy of the photon and $c$ is the speed of light.
3. Photon momentum plays a crucial role in phenomena like radiation pressure and Compton scattering.
4. Even though photons are massless, they can exert force due to their momentum.
5. Photon momentum confirms that light has both wave-like and particle-like properties.

Review Questions

• What equation relates a photon's momentum to its wavelength?
• How does photon momentum explain radiation pressure?
• Why can photons exert force despite being massless?

Related terms

Planck's Constant: A fundamental constant denoted by $h$, used in quantum mechanics to relate energy and frequency of a photon. Its value is approximately $6.626 \times 10^{-34}$ Js.

Compton Scattering: A phenomenon where X-ray or gamma-ray photons scatter off electrons, resulting in a change in wavelength that demonstrates particle-like behavior of light.

Radiation Pressure: $The pressure exerted upon any surface due to the exchange of momentum between photons and that surface.