6H35.50-Stress Plastics by Polarization

Description: This demo shows the stress in a plastic object in between two polarizers that are 90° offset. The colors are seen where the characteristics of the material (levels of stress) allows certain wavelengths of light to pass. Seeing the color yellow means that there is a lack of blue light from the spectrum.


  • Polarizers (set of 2)
  • Thin plastic piece
  • Over head projector

Setup and Demonstration Procedure:

  1. Place polarizers 90° offset on projector screen.
  2. Place the plastic piece directly in between the two polarizer and turn on the projector.
  3. You should see, looking down on the setup, color lines and shapes on the plastic.