# Speed of light

## Homework Statement

Question

Given that the speed of light in a vacuum is 3.0 x 10^8 ms^-1, calculate the speed of light in a diamond of refractive index 2.4.

## Homework Equations

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3. Attempt

So if the refractive index is 2.4, which means 2.4 = sin i / sin r, how can I solve this question? Can anyone give me a helping hand?

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Doc Al
Mentor
You're thinking of Snell's law, but all you need is the definition of index of refraction.

You're thinking of Snell's law, but all you need is the definition of index of refraction.
Thank you but, doesn't the refractive index involves Snell's law?

gneill
Mentor
Thank you but, doesn't the refractive index involves Snell's law?
The other way around, actually. :tongue: Snell's law involves the refractive indexes of the materials.

Look up the definition of refractive index!

Doc Al
Mentor
Thank you but, doesn't the refractive index involves Snell's law?
No. But Snell's law involves the refractive index.

Look up the definition of the index of refraction (which is in terms of velocity): http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html#c2"

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