Hertz was the first to observe (in 1887) that electrons are emitted from a metal surface when light of sufficiently high frequency falls upon it.

This phenomenon is known as the photoelectric effect.

The existence of the photoelectric effect is not surprising because light waves carry energy, and some of the energy absorbed by the metal may somehow concentrate on individual electrons and reappear as kinetic energy. However when scientists looked more closely they found that the photoelectric effect couldn’t be so easily interpreted.

Click on the image to run the simulation.

In this simulation, you can change the colour and brightness of the light, as well as the voltage across the gap.

This interactive simulation allows the student to vary the colour and brightness of the light and observe the effect they have on the emission of electrons. The voltage across the metal electrodes can also be changed and the effect this has can also be observed.

A Java Applet of the photoelectric effect offers an interactive simulation, similar to the one shown in the diagram above. It may be accessed by clicking on the phrase Photoelectric Effect Simulation.

Aim: The aim of this website is to enable students to understand the
       Photoelectric effect, and how the attempts to explain it led to the                Einstein's remarkable insight and in turn to a new understanding of light.

got the Nobel Prize
for his explanation of the Photoelectric Effect.

Einstein Year 2005

Link to Demo