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Polarizing Filter Demo Kit

  • Polarizing Filter Demo Kit
    Polarizing Filter Demo Kit
    Item #: PF-1
  • - +
  • Plexiglas Stress Demo
    Plexiglas Stress Demo
    Item #: PF-6
  • with two 2 in. x 2 in. polarizers
  • - +
Conduct experiments and demonstrations using polarized light.


The Polarizing Filter Demo Kit contains materials and suggestions for more than ten different experiments and demonstrations using polarized light. Includes instructions plus the following:

  • 2 2.75 x 2.75 in. Polarizing Filters
  • 5 sheets of acetate
  • 1 roll optically active cellophane tape
  • 1 Calcite Crystal (Iceland Spar)
  • 1 Plexiglas Stress Demo
  • 1 piece of polyethylene
  • 1 piece of Mica

Plexiglass Stress Demo also available separately. Comes with two 2 x 2 inch Polarizing Filters.


Simple Polariscope: polarized light colorfully reveals the internal stresses imposed on polymer material such as this piece of acrylic, a technique used to model stress distribution patterns in engineering. The polymer sample is placed between two linear polarizer filters configured with their polarization axes at 90 degrees to each other. Many forms of polymer material develop birefringence through photoelasticity when they are compressed or stretched. Follow the link in my profile for info on were to get this and other amazing items featured here on @physicsfun #stresspolarimetry #polarimetry #physics #physicstoy #polaroid #polariscope #polarizer #polarizingfilter #electromagnetism #science #birefringence #photoelasticity #photoelastic #scienceisawesome

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Lesson Ideas

Download the pdf of this lesson!

When two polarizing filters are placed atop one another, they can be transparent or opaque to light. By rotating one of the filters, the transmitted light passing through the filters may be turned 'on' or 'off'. When the filters do not transmit light, the polarizing filters are said to be 'crossed polarizers'. Certain materials such as cellophane tape, Plexiglas, corn syrup, and stretched polyethylene exhibit beautiful colors when placed between two crossed polarizing filters.


  1. Place a piece of mica between two crossed polarizing filters. Each color represents a different thickness of the mica. Try rotating one polarizing filter. Try rotating the mica.

  2. When a piece of Plexiglas is placed between two crossed polarizing filters and squeezed, stress lines appear. Engineers use this method to discover the stress areas in new structural designs.

  3. Place a piece of polyethylene between two crossed polarizing filters. Then stretch the polyethylene by pulling it. Examine the stretched polyethylene sheet between the crossed filters.

  4. Use the special cellophane tape to create designs on a sheet of acetate. Then examine the results by placing it between two crossed polarizing filters. Rotate one of the filters.

  5. If you look at the words on a printed page through a crystal of calcite, you will see double. These natural, nearly transparent crystals exhibit the property of 'birefringence', i.e. they break light into two distinct polarized beams. By rotating a polarizing filter over the crystal, it is possible to view one image at a time. This phenomenon can be displayed using an overhead projector.

About Polarizers:
Only vertically oriented light waves may pass through the polarizing filter on the left. Only horizontally oriented light waves may pass through the filter on the right. If the filter on the left is placed on top of the filter on the right, no light will be able to pass through at all.

If the polarizing filters are aligned parallel to each other, light may pass freely through both filters. By placing transparent objects between two polarizing filters, it is possible to identify those materials which rotate polarized light!

Try sandwiching a plastic baggie between two filters and stretching it. When certain plastics are put under stress, they rotate polarized light. Try placing transparent tape between two polarizing filters. Some brands of tape work better than others. The more layers of tape, the more light is rotated.

Write a Review


1 review
Great Set of Materials
Review star icon Review star icon Review star icon Review star icon Review star icon Feb 11, 2019
This is one of the best set of materials I have ever seen about polarized light. The linear polarized are good sized and decently robust. The PE grips are high quality and very durable. I would highly recommend this set if you are interested in teaching (or learning) about polarized light!
Jeromy Rech

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