The speed of light in glass is 2.0 × 108 m s–1. Does it violate the second postulate of special relativity?

The second postulates describe that the speed of light (for medium vacuum) has same value in all inertial frame. Speed of light in any other medium will be less than that of vacuum using Snell’s law. Snell’s law is given by,



Where,


v=Speed of light in glass


c=Speed of light in vacuum


μ=Refractive index


Thus, it doesn’t violets second postulate of the refractive index because the speed of light in glass is not more than that of vacuum.


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