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Persistence of vision is an optical illusion. When we look at an object, our eyes keep seeing an image of it for a fraction of a second after the object is removed. If several images appear quickly after each other, they seem to merge.

My low-tech example is a piece of cardboard with vertical lines on one side and horizontal lines on the other. When it spins, a word becomes visible.

The high-tech example has a small computer and a single row of LEDs that flicker in a specific order. When the LEDs are moved sideways quickly, letters appear and form a word. The result is best seen in the dark.

A very good video of other low-tech examples may be found onYouTube in “What is Persistence of Vision? (Mr. Wizard)”

Parts for the Low-tech Example

Long shish-kabob stick or knitting needle or similar stick
Corrugated cardboard
Paper for printing
Clear tape
Parts for the High-tech Example

A computer (I used an Apple iMac)
Arduino Uno or another model and its USB cable
Breadboard, preferably attached to the Arduino
7 LEDs of the same color
7 resistors 220 ohms
10k resistor
Push-button switch
Small piece of thin cardboard
Paper clip
Small piece of electrical tape or duct tape”

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