Try This at Home: Benham's Wheel
Illustrated Concepts
C.E. Benham was a toy maker who specialized in designs for spinning tops. One of his designs is only black and white, but gives the illusion of color when spun.
What You Need
- 1 piece of cardboard
- 1 thumbtack
- 1 small round pencil eraser, removed from the pencil
- Printer (or white paper, black marker, and ruler)
- Glue
- Scissors
What To Do
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Make sure you have an adult with you to supervise this experiment.
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Download and print out the Benham's Wheel design (see link to the right), or draw the same pattern onto white paper with a black marker.
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Glue the design to the cardboard and cut around it.
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Push the thumbtack through the wheel from the back. Push the eraser tip onto the pointy end of the thumbtack so that the point is protected. The wheel should be able to spin freely when you hold the thumbtack.
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Make a hypothesis! What colors are on the wheel? Do you think it's possible to see colors on it?
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Spin the wheel! What colors do you see? Have a friend look at it. What colors does she see? What happens when you spin the wheel in the other direction?
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Clean up.
What's Happening
Scientists are not sure what is happening here. Different people see different colors. The color patterns change when the direction of rotation changes. The speed of rotation also influences which colors are seen. Can you devise an explanation for this phenomenon?
Fun Fact
The largest eyes belong to the giant squid; each eye is the size of a basketball!