refraction angles are wavelength dependent, i thought...not the fraction of c by wavelength of photon.

from the wikipedia article on dispersive prisms, for example, though i asked above because i remember this from physics at Fermilab in high school.

> The refractive index of many materials (such as glass) varies with the wavelength or color of the light used, a phenomenon known as dispersion. This causes light of different colors to be refracted differently and to leave the prism at different angles