Cambridge O Level Physics · Syllabus 5054 · Waves
Dispersion of light
What is Dispersion of light?
The separation of white light into the colours of the visible spectrum, which happens because the refractive index of a medium such as glass is slightly different for each frequency. Violet light is slowed most, so it has the largest refractive index and is deviated most; red is deviated least. A prism does not create the colours, it separates colours already present in the white light. In order of increasing frequency the traditional seven colours run red, orange, yellow, green, blue, indigo, violet, and in order of increasing wavelength that order is reversed.
This definition is part of the Waves chapter in Cambridge O Level Physics.
Last reviewed Syllabus 2026-2028