Chapter 43: Problem 3

Question: The speed of yellow sodium light in a certain liquid is measured to be $v~=~1.92\times 10^8~{\rm m/s}$. Find the index of refraction of this liquid with respect to air, for sodium light.

Solution: Assuming that the refractive index of air is unity, $n_{\rm air}~=~1$, then we have that the refractive index of the liquid is the speed of light in vacuum divided by the speed of light in the liquid

$$n_{\rm Na}~=~{2.998\times 10^8\over 1.92\times 10^8}~=~1.56$$