How is the refractive index of a medium related to the speed of light? Give an expression for refractive index of a medium with respect to another in terms of speed of light in these two media?
Refractive index compares the speed of light in a particular medium with the speed of light in vacuum
Relation between refractive index and speed of light:
refractive index (μ) = 
⇒ 
Let the refractive index of medium 1 be μ1 and the speed of light in medium 1 is v1.
⇒ 
………………….. (1)
Similarly;
Let the refractive index of medium 2 be μ2 and the speed of light in medium2 is v2.
⇒ 
………………….. (2)
Dividing (1) by (2)
⇒ 
Hence refractive index of a medium is inversely proportional to the speed of light in that medium.
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