Radiation Budget Activity: Edible Fiber Optics

Grade Level: 5-8

National Science Content Standards

Description of Activity

This activity shows how optical fibers work. Optical fibers are long, thin strands of very pure glass about the diameter of a human hair. They are arranged in bundles called optical cables and are used to transmit light signals over long distances. Optical fibers come in two types:

1. Single-mode fibers are used to transmit one signal per fiber. Used in telephones and cable TV
2. Multi-mode fibers are used to transmit many signals per fiber. Used in computer networks.

Materials

1. 9x13 in baking dish containing:
   • 4 packages of gelatin dessert (white grape works well because it is clear)
   • 2 cups hot water (about ¼ the normal amount)
2. Smaller dish approximately 4x6 containing:
   • 1 package of gelatin dessert (white grape works well because it is clear)
   • ½ cup hot water (about ¼ the normal amount)
3. Penlight or laser pointer
4. Aluminum foil
5. Vegetable cooking oil spray
6. Knife
7. Spatula

Procedures

1. Line the pan with aluminum foil and spray with cooking oil.
2. Mix gelatin with hot water.
3. Pour into the pan.
4. Put pan in the refrigerator to cool and set (about 3 hours)
5. When the gelatin is firm, use the aluminum foil to lift it out and on to a flat cutting board
6. Cut a few straight strips about 1/2 inch wide and a few inches long. (5 inches is a good length)
7. Lift the strips and place them on a flat surface.
8. Shine the penlight or laser pointer into one end of the gelatin strip. Use a piece of white paper to "catch" the light coming out.
9. Bend the gelatin strip into curves and watch the light.

Results and Discussion

1. What happens when the light shines through the gelatin strip?
2. What happens when curves are made? Does the light curve?

Source: