The Ejs Electromagnetic Wave model displays the electric field and magnetic field of an electromagnetic wave.  The simulation allows an arbitrarily polarized wave to be created.  The magnitude of the electric field components and the relative phase between the components of the electric field can all be changed via sliders.  You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.  

Ejs Electromagnetic Wave 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_ehu_waves_emwave.jar file will run the program if Java is installed.  Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.  Additional Ejs models for wave optics are available.  They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

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