Speed of light in refractive material

[benmww]

i understand that the speed of light slows down in a nmaterial with a refractive index greater than one when compared to a vacuum, but is this merely the speed rather than the velocity decreasing, ie does time actually pass slower?
i suppose what i would really like to understand is the mechanism that casues the speed of light to be reduced

 

[Meir Achuz]

The propagation of light is determined by the wave equation.
The speed of the wave is c/n.
Time doesn't depend on n.

 

[Antiphon]

i suppose what i would really like to understand is the mechanism that casues the speed of light to be reduced

The speed of light isn't reduced. The speed of a light wave going through it is reduced.

Its caused by "Dielectric Dispersion". This is when the atoms of the material react to the incoming wave (which is going at c). Their reaction causes the original wave to be absorbed by them but they re-emit a slightly delayed wave. As this happens over and over again along the direction of the the wave's motion, it has the *net effect* of a slower wave. The speed of light is not slowed down in the material.