Ellipse Reflection Model

Move the points. Adjust number of segments. Press Play.


This is a computer model of how sound (or light, etc) reflects inside an ellipse. Points "F" and "G" are the focus points of the ellipse.

ellipse focus points

Example: Stand at one focus point in an elliptical room

A friend could stand at the other focus point and whisper: you would hear them as if they were right with you.


Why is the animation not perfect?

Because it is a computer model.

We could have cheated and just made the line go perfectly to the next focus, but instead we made the ellipse out of a lot of line segments and let the calculations do what they will.

It is a more honest way of showing the effect.

Each reflection is done using the rule of "angle in matches angle out":

reflection: incident ray and reflected ray matching angle


Let the model run for a while, try different number of line segments, or different shapes of ellipse. See what you can discover.

The more line segments, the more accurately the model works.