# How can photons have momentum?

##### 1 Answer
May 28, 2016

Photons have energy which means that they also have momentum.

#### Explanation:

Photons have zero mass and travel at the speed of light. The relationship between the energy, momentum and the speed of light is given by:

$E = p c$

Where $E = \frac{h c}{\lambda}$

$\frac{h \cancel{c}}{\lambda} = p \cancel{c}$

$p = \frac{h}{\lambda}$

$h$ is the Planck constant, $c$ is the speed of light and $\lambda$ is the wavelength of the light and $p$ is the momentum.

So, photons have momentum because they have energy.