Dispersion

Dispersion [The following is from Rainwater/'Light and Color']
Dispersion is the separation of light into its component wavelengths. One method of dispersing a light beam is to pass it through a glass prism--a thick piece of glass with flat non-parallel sides (below). The refractive index of all materials depends slightly on the wavelength of the light. For glass and other transparent materials the refractive index is larger for the short (blue) wavelengths than for the longer (red) ones. Thus, when a beam of white light is passed though a prism, the blue rays will be bent more than the red rays--that is, the light spreads out to form a spectrum. The colors in the spectrum appear in the order of increasing wavelength: violet, blue, green, yellow, orange, and red. Sir Isaac Newton first explained the spectrum. He showed that, contrary to popular belief, the prism did not create the beautiful colors, but only made visible the components of white light.

Scientists make use of dispersion in the analysis of light emitted or absorbed by various materials both on the earth and on other bodies in space.[pg. 45]

[Light and Color, by Clarence Rainwater, Prof. of Physics, San Francisco State College, Original Project Editor Herbert S. Zim, Golden Press, NY, Western Publishing Company, Inc., 1971.

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Disperse vb [ME dysparsen, fr. MF disperser, fr. L dispsersus, pp. of dispergere to scatter, fr. dis- + spargere to scatter -more at Spark] vt [14c] 1a: to cause to break up [police dispersed the crowd] b: to cause to become spread widely c: to cause to evaporate or vanish [sunlight dispersing the mist] 2: to spread or distribute from a fixed or constant source as a archaic: Disseminate b: to subject [as light] to dispersion c: to distribute [as fine particles] more or less evenly throughout a medium -vi 1: to break up in random fashion [the crowd dispersed on request] 2a: to become dispersed b: Dissipate, Vanish [the fog dispersed toward morning] -syn see Scatter