Light travels at the speed of
light. Not completely true. It
travels at 186,000 mps in a VACUUM. In a medium, like
glass, the speed depends on the wavelength of the
light. Longer wavelenths
travel slower. In a prism, blue
light travels faster than green
light, whch
travels faster than red. The faster it goes, the less is refracts (bends). A prism breaks up
light into colors by speed.