PURPOSE: To demonstrate that electric fields are vectors and to demonstrate the vector property of a component of a component

DESCRIPTION: Three polaroids are mounted on a optics track. A light source (large Maglight flashlight) is also mounted directly in front of the first polaroid. It is focused to its smallest and brightest position by turning the lens. A screen is mounted on the other end of the track. You start by placing 2 polaroids on the track and adjusted so no light is shown on the screen. When a third polaroid is inserted between the two crossed polaroids at an angle of 45 degrees with respect to the original axes, light can be seen on the screen.

This demonstrates that the electromagnetic field of which the light consists is a vector. The diagonal polaroid passes a component at 45 degrees with respect to the original light, and the second polaroid passes a component at 45 degrees with respect to the diagonal polaroid. The component of a component is actually perpendicular to the axis of the second original polaroid.

SUGGESTIONS: The real paradox involving this system involves an analysis of single photons. How can a single photon originally polarized parallel to the first polaroid have its angle of polarization rotated 90 degrees and exit the final polaroi d polarized perpendicular to its original plane of polarization.

EQUIPMENT: Optics track with three polaroids, large Maglight flashlight, optics track screen.

SETUP TIME: 30 min.