Editing Wave (section)

=== Dispersion ===
[[File:Light dispersion conceptual waves.gif|thumb|right|270 px|Schematic of light being dispersed by a prism. Click to see animation.]]
{{Main|Dispersion relation|Dispersion (optics)|Dispersion (water waves)}}

Dispersion is the frequency dependence of the [[refractive index]],  a consequence of the atomic nature of materials.<ref name=hecht>{{Cite book |last=Hecht |first=Eugene |title=Optics |date=1998 |publisher=Addison-Wesley |isbn=978-0-201-83887-9 |edition=3 |location=Reading, Mass. Harlow}}</ref>{{rp|67}}
A wave undergoes dispersion when either the [[phase velocity]] or the [[group velocity]] depends on the wave frequency. Dispersion is seen by letting white light pass through a [[prism (optics)|prism]], the result of which is to produce the spectrum of colors of the rainbow. [[Isaac Newton]] was the first to recognize that this meant that white light was a mixture of light of different colors.<ref name=hecht/>{{rp|190}}