PURPOSE: To demonstrate that electric fields are vectors
and to demonstrate the vector property of a component of a
component
DESCRIPTION: Two crossed polaroids are placed on the overhead preventing
light from passing to the viewers. 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 passing through the system.
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.
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 polaroid polarized perpendicular to its
original plane of polarization?
EQUIPMENT: Polaroids.
Updated by Jun Qi in 3/22/2000