Physics Dept. Demonstration Manual

DOP 08.1 - Polarization

Objective:

To show the action of polarizer and analyzer.

 
Apparatus:  
  • Polarizers (2 disks)
  • Disc support stand
  • Overhead projector
  • Plastic stress samples
  • Sample-holding sticks

Method:

For demonstrating polarized light, the two discs are placed in the support stand on an overhead projector. When the top disc is rotated, the intensity of the transmitted light drops to a minimum as the axes of polarization are aligned. Any of the samples placed on the sample-holding sticks between the two polarized sheets will produce interference colors. In the case of things like plastic "French curves," interference is due to built-in stresses.

Note:

Wiping or scratching the polarized discs leaves very fine scratches, resulting in random polarization. Also, handle and rotate the discs by the metal edge only.