Fresnel lenses to show.

Fresnel lenses to show. There are many examples of Fresnel lenses that can be shown to the class. One is a plastic Highway Blinker light (diverging lens), which works with a 6 volt battery. One is a glass Fresnel converging lens (f.l. 1.5"), possibly from an old traffic light. One is a flat plastic diverging lens (f.l. -5") mounted on a wood frame; everything looks smaller when viewed through it. One is a flat plastic converging lens from an overhead projector (f.l. +10"). There are several other examples not shown above.