dispersion relation

Dispersion, in wave motion, describes how individual waves travel at speeds that vary based on their wavelengths. This relationship between a wave's frequency and its wavenumber is known as a dispersion relation.1

Waves are considered nondispersive if their velocity remains constant regardless of wavelength. Conversely, dispersive waves exhibit a velocity that changes with wavelength. A common example is ocean waves, where speed is related to wavelength. In transparent materials like glass, light waves disperse because the speed of light varies with the material's refractive index for each wavelength, causing white light to separate into its constituent colors, as seen in prisms and rainbows. This phenomenon is called angular or chromatic dispersion.12