# Formula Photon Photon energy Frequency

## Photon energy

`\( W_{\text p} \)`Unit

`\( \mathrm{J} \)`

Photon energy is the energy of a single photon (light particle). You can calculate it with the help of the light frequency \( f \). For example, if the light has the frequency \( f = 10^{15} \, \mathrm{Hz} \), then the energy of a photon is:

`\begin{align} W_{\text p} &= 6.6 \cdot 10^{-34} \, \mathrm{Js} ~\cdot~ 10^{15} \, \mathrm{Hz} \\\\ &= 6.6 \cdot 10^{-19} \, \mathrm{J} \end{align}`## Frequency

`\( f \)`Unit

`\( \mathrm{Hz} \)`

Frequency of electromagnetic radiation. For example, the frequency of green light is in the range \( f = 5.5 \cdot 10^{14} \, \mathrm{Hz}\).

The frequency can be written with the wavelength \(\lambda\) and the speed of light \(c\) as follows:`$$ f = \frac{c}{\lambda} $$`

## Planck's constant

`\( h \)`Unit

`\( \mathrm{Js} \)`

Planck's constant is a physical constant from quantum mechanics and has the value:

`$$ h ~=~ 6.626 \, 070 \, 15 \,\cdot\, 10^{-34} \, \mathrm{Js} $$`