Demonstrate total internal reflection with a laser pointed through a light pipe or fiber optic bundle.

We have two acrylic light pipes and a bundle of fiber optic strands. Light is transmitted along the device by total internal reflection. You'll want a reasonably dark room for this demo:

• The fiber optic bundle isn't as bright as shown in the photo below, but the tips will appear bright, even as you wave the bundle to make the fibers flex.
• The light pipes also show that light is scattered sideways along the length of the pipe, and carried through to the end. This is especially noticeable with the spiral pipe. The wavy pipe is made of "smoked Lucite™", and is the best one for demonstrating total internal reflection; change the angle of the laser so that the path clearly shows the laser bouncing along the pipe

LDL-B3. You'll need a laser pointer – green is the most visible by a class. Ask your favorite astronomer, or less-intimidating neighbor, if don't have your own.