When white light strikes the surface of a compact disc, something fascinating happens. The microscopic tracks on the CD act like a diffraction grating, splitting the white light into its component colors and creating a beautiful rainbow spectrum on a nearby screen.
The key to understanding this phenomenon lies in the structure of the compact disc itself. A CD contains thousands of microscopic tracks, each separated by approximately 1.6 micrometers. This regular spacing is crucial because it creates what physicists call a diffraction grating - a surface with regularly spaced features that can split light into its component wavelengths.
Here's what happens during the diffraction process. When white light hits the CD surface, the regularly spaced tracks cause the light waves to bend at different angles. Each wavelength of light - red, orange, yellow, green, blue, indigo, and violet - diffracts at a slightly different angle. This separation of wavelengths creates the beautiful spectrum we see projected onto a screen.