Low Cost Demonstrations In Optics Created by Alyssa Cederman and Jessie Segal Advisor: Dan MacIsaac Organization: EURP Buffalo State College Department of Physics

Purpose Traditional optics demonstrations are expensive and difficult or impossible for physics teachers to construct. Our goal was to convey physics concepts visually with very little cost and time required in constructing apparatus using a modern green laser diode.

Low Cost Poisson’s (Arago’s) Spot Apparatus

Poisson's (Arago’s) Spot A map pin in a laser beam causes diffraction patterns. The resulting patterns are a bright spot in the center of the shadow and surrounding internal rings. The map pin can be replaced with other small objects for different diffraction patterns.

Low Cost Variation of Young’s Double Slit Apparatus

Diffraction with Hair or Wire Light bends around a hair and causes diffraction patterns. The distance to the fringes from the center (y n ) can be calculated with: And for dark fringes:

Low Cost Apparatus for Varying Index of Refraction

Varying Index of Refraction Using Sugar Solution The sugar solution bends the laser light, and the mirror reflects the light. The laser beam bends due to the varying index of refraction. Refraction can be calculated by using Snell’s Law:

Apparatus for Total Internal Reflection (TIR)

Total Internal Reflection (TIR) Using a Soda Bottle The critical angle is found by a modification of Snell’s Law:

Apparatus for Newton’s Rings

Newton’s Rings Using Microscope Slides The angle between two microscope slides can be found by using Newton’s Rings with the math below:

Conclusions Optics demonstrations can be created using common household items and office supplies. Green lasers are now cheap, and they produce much brighter results compared to red HeNe or diode lasers or expensive sodium light sources.