The EJS Photoelectric Effect model simulates the Photoelectric effect discovered by Hertz in 1887 and described theoretically by Einstein in 1905. Light of a given frequency (energy) shines on a metal in a vacuum tube. If the energy of the photons is greater than the work function of the metal, W, electrons are ejected and can form a current in an external circuit. These photoelectrons will have a kinetic energy if the energy of the light is greater than the work function. If subjected to an electric potential between the plates in the tube, the electrons excited from the metal will be accelerated resulting in an increase, decrease, or stopping of the current. This model provides controls for the frequency of the light source and the external potential on the electron tube. An ammeter allows users to take data for the photo-current.


The EJS Photoelectric Effect model was created using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_qm_photoelectric.jar file will run the program if Java is installed.

Please note that this resource requires at least version 1.5 of Java (JRE).