# Illustration Capacitor with set accelerating voltage for photoelectric effect

A plate capacitor consists of two electrodes (capacitor plates). An accelerating voltage $$U_{\text B}$$ is set between the electrodes.
An electrode is now illuminated with photons of the energy $$h \, f$$. The photons land on the electrode surface and eject electrons in the process. Because of the applied accelerating voltage, the electrons are accelerated to the positively charged capacitor plate. After arriving at the opposite plate, they pass through the ammeter and cause a measurable electric current (photocurrent).