6H35.50-1 - Stress Kit
Demonstrate how stresses in a material can be seen in polarized light.
Place unit on overhead projector or on a document camera (if lit from below). Make sure that the screw assembly is out of the viewing area unless requested. Focus the projector (camera). Place serveral different items on an anti-slip mat to protect from scratches and minimize sliding off table.
**Important to remind professors about the lighter and glass**
Place different samples on to the staging area to view internal stresses.
With the different samples, you can show: stress around cutouts (point, square, round, keyhole), layered mica, safety glasses, screws v. nails, thermal stresses in glass (using lighter). Plastic pieces can be *gently* squeezed to increase stresses.
Large glass dounut, show stress by cooling down.
There are several polarization examples included in this kit, all of which use the overhead projector in the same manner.One polaroid is located in a rotatable stage located above the main platten where the other non rotatable polarizer is located.All objects placed on the main platten are viewed thru two polarizers and projected on the screen.
On the bottom of the apparatus is a fixed linear polarizer. On the top of the apparatus is a rotatable linear polarizer. These can be adjusted so that varying amounts of light get through. The samples used are optically active materials. They rotate the polarized light and the amount of rotation depends on the color of light and the thickness of the material. This rotation of the polarized light means that not all of the light entering the sample will exit through the second polarizer, and allows us to see a representation of the internal stresses of the samples.