It is a lot of fun to play with prism with light beams.
You can change the shape of the prism or direction of light source with mouse drag motion.
The simulation also shown the intensity of each refracted light path.
I hope you can enjoy playing with it as I do.

VIEW or DOWNLOAD ejs xml source
then click to translate strings for selected locale.

Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.