Og-2 Strain Polarisation
Aim
To demonstrate strain birefringence.
Apparatus
- Overhead projector
- Polaroid sheets
- Perspex models
- Strained glass
Perspex Models under strain.
Description
The perspex models and the strained glass (caused by rapid cooling) are placed on the overhead projector with the polaroids in the crossed position. Strain present in the glass or induced in the perspex causes the object to become anisotropic and birefringent. This results in visible stress lines due to interference colours.