Question

What determines the speed of light in a medium?

Answer 1

The refractive index `(n)`

Explanation:

Each and every object in the universe has a refractive index, called `n`. This determines the speed of light when it passes through it.

The formula for the refractive index is

`n=c/v`

where

`c` is the speed of light in a vacuum `(3*10^8 \ "m/s")`

`v` is the speed of light through a certain medium