One Line Answer
What do you mean by the statement that the refractive index of diamond is 2.42?
This statement means that diamond is 2.42 times optically denser than air. Thevelocity of light in diamond is equal to `1/2.42` times velocity of light in vacuum. Thus, vd = `(3 xx 10^8)/2.42` = `1.24 xx 10^8` m/s.
Concept: Refraction of Light from a Plane Transparent Surface
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