Gelatin Prism

Author: Wayne Goates: Kansas Polymer Ambassador

Concept: Refraction (bending) of light.

Materials Needed:

Knox Gelatin®, 21-grams (3-packets) Glycerine, 5-mL
Razor blade or suitable cutting implement Distilled water
sandwich plastic container or similar smooth-bottomed container Hot plate
Light pen or laser pen Stirrers (popsicle sticks)
Beaker, 250-mL  Zip Loc bags (sandwich size)
100 mL graduated cylinder .

Safety Considerations:

There are no safety hazards with materials used in this experiment. The prisms may become moldy after storage for several days or more.  If that occurs, they should be disposed of in the trash.
All materials used in this experiment can be safely disposed of in the trash.
1.  Making a gelatin prism: 2.  Point the laser or pen light through the base of the triangle.  The light should bend as it passes through the matrix of the gelatin prism.  It may be necessary to darken the room to see the refraction or bending of the light through the prism.
Diagram: This is what shape your prism should have.

A beam of light traveling through a liquid, a solid or through air is invisible unless something is put into the beams path which can deflect the light.  Refraction is the bending of light rays as they pass from one medium to another.  The speed of light in air and the speed of light in a solid medium (such as the gelatin) is different.  As the light will be going from a less dense material (air) into a more dense one (gelatin), this causes the light to change direction or bend.
Activities:"Doing" science by asking questions.