Índice de refracción

The transcript explains the concept of a medium in optics, defined as the ratio of the speed of light in a vacuum to its speed in the medium. It further discusses the refractive index, using glass as an example, where a refractive index of 1.5 indicates that light travels 1.5 times faster in a vacuum than in glass.

What does a refractive index of 1.5 indicate about light's speed in a vacuum?

Explain the relationship between the speed of light in a vacuum and the speed of light in glass.