Newton's Disc

What is Newton's Disc?

Sir Isaac Newton created this disc to demonstrate that white light is composed of all the colors of the visible spectrum. When the disc spins fast enough, the colors blend together and appear white or gray due to persistence of vision.

Persistence of Vision

Your eye retains an image for about 1/16th of a second after the source is removed. When the disc spins rapidly, each color's reflection reaches your eye before the previous image fades, causing the brain to blend all colors together into white.

Try This

• Slow speed: Watch individual colors rotate
• Medium speed: Observe colors starting to blur
• Fast speed (>10 rev/s): Colors blend towards white
• Toggle 3 vs 7 sectors to compare how different color combinations blend

The Visible Spectrum

Key Points

• White light contains all colors of the rainbow
• The disc proves color addition — not subtraction
• 3 primary colors (RGB) blend to a purer white than 7 sectors
• This principle is used in color TV and computer screens
• Named after Sir Isaac Newton (1642–1727)