Dispersion is the spreading out of light into its colours. Dispersion in a prism occurs because the refractive indicies of many materials (including glass, perspex and water) depend on the colour (wavelength) of the light.[list][*]White light is incident on a 60°, 60°, 60° prism. Use the slider to change the initial angle of incidence.[/*][*]You can set the refractive index for red light (n[sub]r[/sub]) and the difference in indicies for red and blue light (n[sub]b[/sub]-n[sub]r[/sub]).[/*][*]The [i]angle of dispersion[/i] is the angle between the red and blue rays after they have refracted through the prism.[/*][*]The [i]angle of deviation[/i] is the angle between the line of the incident ray and the final refracted red ray.[/*][/list]