I understand that as the frequency of an electromagnetic wave increases, its refractive index decreases in a material. According to this, red light would have a higher refractive index than blue light (is my mistake here? why?). Since sinI/sinR = n (where I is the angle of incidence, R is the angle of refraction, n is the refractive index), and if I is a constant, for red light R would be smaller than that in blue light. If so, then when a beam of white light shines into an upright triangular prism, inside the prism the red light should be 'below' the blue light. But this is contrary to the picture depicted here: http://en.wikipedia.org/wiki/File:Dispersion_prism.jpg" [Broken] Where is my fault?