Hi I have a good understanding of the refraction of light and the reason it occurs etc. but what is confusing me is the exact reason for the "slowing" and hence bending of light inside a transparent material. What are the exact properties that allow a transparent material to slow a beam of light? What does the slowing of a light beam attribute to the bending of a light beam? And Could some one please explain or refer me to a site that does explain the phsyics behind the refraction of light.