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Rainbow Peephole™
COLOR by Redirecting (Diffraction)
Optics Suitcase

Have the teacher pass out the Rainbow Peephole™ Theme Packets, but ask the students not to open them yet. When everyone has their own packet, proceed as follows:

  • Remove the flashlight and the peephole from your packet, hold them up, and identify them. Ask the students to remove theirs and figure out what to do by referring to the image of the young lady on the back of the packet.

  • During the “oohs” and “ahs”, ask the group, “Where does the color come from?” [Many children will answer that the colors comes from the peephole. Tell them that the colors come from the white light in the flashlight.]

  • You can ask any or all of the following questions:

    • Do you see a regular pattern? Describe it.
    • Identify all of the colors. Are they the same in each spot?
    • Does the pattern change if the flashlight is close or far from the peephole? How?
    • Do you see colors from other people's flashlights, even those far away from you?
    • Do you see colors from the room lights?

  • Hold up the packet and show the picture on the front. Describe this as a highly magnified photograph of the surface of one side of the clear plastic in the peephole. It is taken with an instrument called an atomic force microscope. [Optical engineers develop instruments like this.]
  • Note that the scale is in microns, that a human hair is 30 to 80 microns wide, and that the plastic has a regular array of small bumps across it that are only two microns high - too small to be seen or felt.
  • The bumps are packed so closely together that about fifty of them could fit inside a human hair. These bumps are responsible for redirecting the light coming into the peephole, depending on its color. Point out the similarity between the regular array of bumps and the pattern seen through the peephole.
  • Ask for a show of hands by everyone who wants a cell phone. With the transparency (Figure 5) explain how tele-communications uses fibers and lasers to divide light from one beam into many, each with a different color. This is the key to unlimited numbers of conversations all over the world at the same time. [Optical engineers do this stuff.]
  • Ask everyone to seal the flashlights and peepholes back into the packets. Tell them the packets are theirs to keep. Suggest that they can reveal to family members the secret of seeing colors in white light through diffraction.

Copyright by Stephen D. Jacobs, Rebecca L. Coppens and Christine Andrews-Angelo
December 24, 2001

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This site was last updated June 3, 2005.
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