Conceptual Index of Refraction Question.

AI Thread Summary
The discussion centers on the index of refraction formula n = c/v, which indicates how much faster light travels in a vacuum compared to a medium. A suggestion is made to express it as n = v/c to clarify how much slower light moves in a medium, potentially simplifying understanding. The conversation highlights that this alternative perspective could reduce confusion by stating that light in glass is 2/3 slower than in a vacuum. However, it is noted that Snell's Law and the concept of the index of refraction were established before the speed of light was accurately measured, making the original definition more about refraction than speed. The historical context of the index of refraction's development is acknowledged as a factor in its current formulation.
fallen186
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We have the index of refraction formula of n = \frac{c}{v} which essential states how much of a factor light travels faster in a vacuum than in this medium. Why don't they just have it as n=\frac{v}{c} so it states fractionally how much slower light travels in the medium than the speed of light.

Its like saying light in a vacuum is going 1.5 times faster than it would if it was in glass compared to "light going through glass is 2/3 slower than going in a vacuum".

I feel like it would be simpiler to just to say 2/3, and less confusing.
 
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I agree with you.

However, Snell's Law for the refraction of light predates the first reasonable measurement of the speed of light. The index of refraction was initially used to explain light refraction at an interface, and the speed of light was not a consideration in its definition.
 

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