# Formula Photoelectric Effect (Cutoff Wavelength, Work Function) Work Function

## Work Function

Unit
Work function is the energy that must be expended to knock an electron out of a solid (e.g. out of a metal plate). Usually, the work function is given in the unit "eV" (electron volt):$$1 \, \mathrm{eV} = 1.6 \cdot 10^{-19} \, \mathrm{J}$$

## Cutoff wavelength

Unit
Cutoff wavelength is the minimum wavelength that light must have in order to be able to knock electrons out of a metal plate.

## Planck's Constant

Unit
Planck's constant is a physical constant that occurs in the equations when the phenomenon under consideration shows a quantum mechanical character. The Planck's constant has the value: $$h ~=~ 6.626 \cdot 10^{-34} \, \mathrm{Js}$$

## Speed of light

Unit
Speed of light (in vacuum) is a physical constant and has the value:$$c ~=~ 3 \cdot 10^8 \, \frac{\mathrm m}{\mathrm s}$$