Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12

# The Speed of Light in Glass is 2.0 × 108 M S−1. Does It Violate the Second Postulate of Special Relativity? - Physics

Short Note

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

#### Solution

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=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.

Concept: Maxwell'S Laws
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 2
Chapter 25 The Special Theory of Relativity
Short Answers | Q 1 | Page 456