# Formula: Photoelectric Effect Energy    Frequency    Voltage    Planck's Constant

## Work function

Unit
Work function is the energy that must be spent to eject an electron from a solid (e.g. from a metal plate). It is usually expressed in units of "eV" (electronvolt).

## Frequency

Unit
Frequency of the light with which, for example, a metal plate is illuminated.

## Stopping voltage

Unit
Back voltage is the voltage between two capacitor plates. This voltage is adjusted so that the electrical energy $$e \, U_{\text G}$$ exactly compensates the kinetic energy of the ejected electron.

## Elementary charge

Unit
The elementary charge is a physical constant and is the smallest, freely existing electric charge in our universe. It has the exact value: $$e ~=~ 1.602 \, 176 \, 634 ~\cdot~ 10^{-19} \, \mathrm{C}$$

## Planck's Constant

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

## The Most Useful Physics Formula Collection on the Internet

+ Perfect for high school and undergraduate physics students
+ Contains over 500 illustrated formulas on just 140 pages
+ Contains tables with examples and measured constants
+ Easy for everyone because without vectors and integrals