Newton’s Optical Color-Wheel Fusion Spinner
Persistence of Vision & Additive Color Mixing on a Twirling Disc
Household Scraps & Tools Needed
Assembly Instructions (5 Steps)
Follow each step carefully. Work together to clean waste, score precise cuts, align pivots, and test kinetic mechanics.
Draw the 7-Sector Rainbow Spectrum Disc
Divide a paper circle the size of a CD into 7 equal wedge sectors. Color them in rainbow order: Red, Orange, Yellow, Green, Blue, Indigo, and Violet. Glue it onto the CD.
Pierce Dual String Holes in Bottle Caps
Glue a bottle cap over the center hole on both sides of the CD. Pierce two small holes 1cm apart through both bottle caps and the CD center.
Thread & Tie the Continuous Twine Loop
Thread a 90cm piece of string through one hole and back through the other hole. Tie the two loose string ends together into a secure square knot to form a continuous loop.
Wind Up the Elastic String Rotor
Slip index fingers through the outer string loops on each side. Swing the CD in circular motions like a jump rope to wind the string into tight twists.
Pull, Relax & Watch Colors Vanish into White
Pull your hands apart firmly to spin the CD at high speed. As it reaches full unwind, relax tension slightly so momentum rewinds the string in reverse. Watch the rainbow blend into pure white!
Persistence of Vision & Additive Color Synthesis
Human retinal photoreceptors retain an image for approximately 1/16th of a second (Persistence of Vision). When colors alternate faster than the optic nerve’s refresh rate, the brain blends red, orange, yellow, green, blue, and violet into perceived white/gray light.
White light is the composite combination of all visible rainbow wavelengths.
Skills Your Child Develops with This Project
Optics & Color Science
Discovering how the brain perceives moving visual data and color combinations.
Rhythmic Bimanual Pulling
Coordinating pull-and-slack timing to keep the string spinner accelerating continuously.
Visual Pattern Design
Experimenting with black-and-white Benham disc patterns to create subjective illusory colors.
Fun Family Experiments & Mini-Games
The Ghost Color Illusion Challenge
Draw a black-and-white Benham top pattern on the reverse side of the CD and spin it to see what pale colors your eyes hallucinate (red, green, or brown).
The Continuous 60-Second Rhythm Run
Master the pull-and-relax cadence to keep the spinner whirring continuously for 60 seconds without having to manually rewind the string.
Parent Note:
Isaac Newton used this exact experiment in 1672 to prove that white light is a blend of all rainbow colors. Simple, timeless, and scientifically profound.
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