CBSE-XI-Physics
47: The Special Theory of Relativity
- #1The speed of light in glass is 2.0 × 108 m s-1. Does it violate the second postulate of special relativity?Ans : According to the second postulate of special relativity, the speed of light in vacuum has the same value c in all inertial frames.
The speed of light in glass is 2.0 × 108 m s-1, but it doesn't violate the postulate as light follows Snell's law, according to which the speed of light in any refractive medium gets reduced by a factor `` \eta `` such that `` v=\frac{c}{\eta }`` (where `` \eta `` is the refractive index).
Thus, the speed of light in glass is 2.0 × 108 m s-1 as `` \eta `` in this case is 1.5.
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