What Is Newton's Theory of Color?

Sir Isaac Newton began trying to explain what he called the "phenomenon of colors" in the late 1660s. He experimented with light and color as a way of understanding more about the physics of light itself. He published his experiments and the resulting theory of color in 1672.

Theory

Newton's Theory of Color states that objects appear to be certain colors because they absorb and reflect different amounts and wavelengths of light. Newton used prisms to prove that white light is actually made up of waves of different colors. This was a radical and controversial idea for the 1660s. At the time, most scientists thought that prisms somehow added color to light.

Prism Experiment

Newton used two prisms to prove that the color was in the light, not in the prism. He placed the first prism in a beam of sunlight and projected the rainbow spectrum - red/orange/yellow/green/blue/indigo/violet - on a wall 22 feet away. To further prove that those colors were components of the light, he inserted another prism into the path of the projected spectrum and reconstituted the beam of light so that it shone white again.

Light Waves

Newton discovered that light behaves a lot like waves, bending around objects, much as water flows around them. When light strikes a prism, the different waves of color are bent to different angles, which creates the rainbow spectrum we see. Red light bends the least and violet light bends the most.

Color Wheel

Newton also invented the color wheel. He took the colors refracted by the prism and placed them in a segmented circle that was based on the mathematical calculations of their wavelengths. he placement provided artists with a chart demonstrating that the primary colors (red/yellow/blue) appear opposite the secondary colors with the most contrasting wavelength (red-green/yellow-violet/blue-orange). These colors provide the greatest optical contrast when placed side-by-side.

Applications

The color wheel also illustrated how all colors could be created by combining the primary colors in different proportions. Colors that appear near each other are considered analogous colors and are always harmonious when used together. Crossing the color wheel to choose contrasting or complementary colors creates visual drama. Using this information artists and designers create visual effects that can attract or repel us. Lighting designers use colored light to change the look of a space and create more interesting shadows.

Significance

Because of Sir Isaac Newton, we now understand that all color comes from light reflection and refraction. We are able to use color to help us communicate ideas and feelings and to explain why the sky is blue and apples are red.