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Why can a prism separate white light into different colors?
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When white light is spread apart by a prism or a diffraction grating, the colours of the visible spectrum appear. The colours vary according to their wavelengths. Violet has the highest frequencies and shortest wavelengths, and red has the lowest frequencies and the longest wavelengths.
A prism separates white light into its constituent colors through a process known as dispersion. This occurs because the refractive index of the transparent materialāsuch as glassāvaries depending on the wavelength of the light passing through it.12
When white light enters the prism, each component color (or wavelength) is refracted, or bent, by a different amount. Shorter wavelengths, which correspond to the violet end of the spectrum, are bent the most, while longer wavelengths toward the red end are bent the least. Because the speed of light in a medium depends on its wavelength, the prism causes the incident beam to fan out, effectively spreading the white light into its individual spectral colors.32