Moiré Patterns

Have you ever looked through an electric fan and seen a shimmering pattern of light and dark areas around the center? This is a type of optical illusion called a moiré (pronounced mwar-ay). It happens when two see-through patterns of lines overlap, like the wires on the front and back of the fan.
Try this easy experiment to make your own moiré patterns!
How we did it:
Materials List
- plastic canvas - used in needlepoint
- lazy susan
- scissors
- black paint
- sponge
- smartphone - optional
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Step 1
Gather your materials.
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Step 2
Cut the canvas into two 6" squares.
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Step 3
Paint both sides of each canvas black. Let them dry for at least 30 minutes.
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Step 4
Place one of the canvases in the middle of the lazy susan.
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Step 5
Hold the second canvas centered over the first canvas and slowly spin the lazy susan. What do you observe? What happens when you spin faster? What about slower?
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Tip!
If you have trouble seeing the patterns, ask a friend to take a video of you spinning the lazy susan from directly above. In a video, you can see the patterns moiré clearly!
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Learn More!
When you spin the canvases, the interaction you see between them is a kind of optical illusion. You see moiré patterns because it’s tough for your brain to process lots of criss-crossing lines. Instead, it simplifies things into a pattern of dark areas (where the lines are close) and light areas (where they aren’t).
As the bottom canvas rotates on the lazy susan, it creates a new pattern with the one you’re holding steady above it. That’s moiré!
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