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Q & A: Index of refraction of diamond

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Most recent answer: 12/22/2015
Why is the refractive index of diamond the highest?Can it be explained by ray diagrams?
- alisha (age 16)
Although diamond has a very high index of refraction, 2.42, there are several other substances with higher values, for example Rutile (TiO2) with an index varying from 2.6 to 2.9.   

A ray diagram doesn't explain the 'Why' of index of refraction, it explains the 'How it affects light' aspect of the phenomenon.    The real explanation involves the atomic structure of the substance and its electronic properties.  I recommend you look at the wikipedia article for further detailed information. 


(published on 10/22/2007)

Follow-Up #1: Optical anisotropy

Is refractive index and hence speed of light depends on the direction within a material? Mean to say is velocity of light different as the light travels along different directions in the crystal? If yes, then why this happens?
- Haseeb Ahmad (age 21)

Yes, in many materials the index of refraction is different along different directions. That means that the velocity of light is different along different directions. The reason is that the index of refraction is caused by the response of charged particles (mostly electrons) to the light wave. In crystals whose structure is different in different directions, it's easier for the electrons to respond in some directions than in others. That also causes different speeds for different polarizations of light traveling in some directions.

Mike W.

(published on 12/22/2015)

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