Jello Optics
Overview: You can buy off the shelf lenses, but you are limited in size and shape. At some point it also becomes cost inhibitive. With a sheet of Jello you can cut “lenses” of any shape and size you want for a relatively low cost.
Supplies: Sugar free, light color Jello packet(s) (lemon and orange are best), water, sheet pans, green and red laser pointers
Objectives: Create your own Jello lenses to see how light bends off of different angled surfaces
Setup:
- Follow the recipe for Jello jigglers, which calls for a 1:1 ratio of jello to boiling water
- Cut the Jello into various shapes, or let the kids cut their own shapes
How to run the demo:
- Put the Jello shapes out on the table on flat plates or paper towels
- Shine the lasers through the Jello shapes and observe how each of the lasers lights are bent
What’s Happening?
Every material has its own index of refraction, or the measurement of how much light will bend, based on its density. When light moves from air, with an index of refraction of 1, to Jello, with an index of refraction of 1.38, the change in density will change the speed at which the light is moving and it will bend at a specific angle. The index of refraction of glass is 1.51 and for water it is 1.33. Since Jello is mostly water, it will bend very similar to water.
Try this:
- Instead of cutting traditional lens shapes, cut light pipes and show another optics phenomenon called total internal reflection, or TIR.
Learn more: (external links)