CMY Protractors

These overlapping cyan, magenta and yellow protractors are resting on white paper and are illuminated with white light. The light reflecting off the paper consists of the ROYGBIV spectrum. This spectrum of light colors is often thought of as RGB light, consistent with the three basic color-sensing cones of the retina. Where the protractors overlap, different colors are observed due to the phenomenon of color subtraction. Where the magenta and the yellow protractors overlap, the color red is observed. This is explained by the fact that the yellow protractor subtracts (filters out by absorption) the blue light and the magenta subtracts green light; only red light remains and that's what the eye sees. Similarly, blue is observed at the locations of overlap of the magenta and the cyan protractors. The magenta protractor subtracts the green light and the cyan protractor subtracts the red light, leaving the blue light for the eye to see.

 

Learn more about color subtraction at The Physics Classroom website.

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