Polaroids And Gooseneck Lamp
To demonstrate polarization of light.
Goose neck lamp, large round polaroids on base, extra square polaroid.
The first polaroid polarizes the light. Rotating the front polaroid causes the light to become alternately brighter (polaroids aligned) and dimmer (polaroids crossed). Insert a third polaroid between the two crossed polaroids at a 45 degree angle to show that the electric field is a vector, and to demonstrate a component of a component. Argue with your students about what happens in this experiment when the light passes one photon at a time.
Hollis N. Todd, Polarization of Light - Basic Theory and Experiment, Bausch & Lomb Inc. (1970). H. Richard Crane, How Things Work: How Does the Honeybee Sense Polarization?, TPT 27, 504-505 (1989).