Refractive index

The video explains the concept of refractive index, which is the ratio of the speed of light in a vacuum to its speed in a given medium. It uses the example of glass with a refractive index of 1.5, indicating that light travels 1.5 times faster in a vacuum than in glass.

Explain the significance of the speed of light in a vacuum versus in a medium.

What implications does the refractive index have on the behavior of light in different materials?