My name is Alexander FufaeV and here I write about:

# What is the Planck's Constant?

The **Planck's constant** \( h \) is a physical constant that appears in equations whenever the equation describes quantum phenomena. For example, it appears in the light quantum hypothesis:

$$ \begin{align} W_{\text p} ~=~ h \, \class{violet}{f} \end{align} $$

In this equation Planck's constant connects the energy \( W_{\text p} \) of a photon (light particle) with the light frequency \( f \). From this equation you can also read the unit of the Planck's constant, if you rearrange the equation for \(h\): **Js (Joule seconds)**.

You can measure the value of the Planck's constant, for example, using the photoelectric effect. It has the value:

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