1.
Does the velocity of light change accordingly to
medium?
The speed of light is considered the universal speed limit. Yet, the measured speed of light varies with the change in optical density of the medium. Light propagates faster in the rarer medium and slower in the denser medium.
In other words, it also varies along with the change in permittivity and permeability of the medium, as the speed of light is given as the reciprocal of the square root of the product of permeability and permittivity of the medium.