Newton’s Disc beautifully demonstrates additive color mixing. When the disc, divided into segments of rainbow colors, spins rapidly, our eyes blend the colors together, perceiving them as white light. This occurs because white light is actually a combination of all colors in the visible spectrum. Newton used this experiment to show that white light is not pure but a mixture of colors, revolutionizing our understanding of light. The rapid spinning causes our eyes to stimulate red, green, and blue