The Ejs Reflection and Refraction between Taut Strings model displays the motion of a traveling pulse on a string when it is incident on a change of string density.  The type of initial pulse type can be changed via slider and the width, amplitude, and speed via text boxes.  The relative mass densities of the two strings can be set by setting the reflection coefficient via a slider.  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 Reflection and Refraction between Taut Strings 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_strings.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 motion 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).