# Formula Photon Photon energy    Frequency

## Photon energy

Unit
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

Unit
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

Unit
Planck's constant is a physical constant from quantum mechanics and has the value:$$h ~=~ 6.626 \, 070 \, 15 \,\cdot\, 10^{-34} \, \mathrm{Js}$$