# What is refractive index of a hollow glass container with a liquid inside?

Suppose that a thin hollow glass slab with a refractive index of $$1.5$$ contains a liquid inside, which has a refractive index of $$\mu$$, and $$\mu \neq 1.5$$. If I now send a laser light at the medium and measure the angle of refraction, will it now be $$sin^{-1} (\frac{sin i}{\mu})$$ or $$sin^{-1} (\frac{sin i}{1.5})$$? So will the refractive index of this medium become $$\mu$$ or does it remain $$1.5$$?

For an interface between two mediums $$A$$ and $$B$$ with absolute refractive index $$\mu$$ and angle from normal $$i$$, the relationship $$\mu_{\rm A}\sin i_{\rm A} = \mu_{\rm B}\sin i_{\rm B}$$ can be used.
Can you please clarify what is meant by $$i$$ - is it the angle of incidence on the hollow glass? If so, according to Snell's law you may write ($$\alpha$$ is angle of refraction in the glass and $$\beta$$ is the angle of refraction in the water): $$\sin i = 1.5 \sin \alpha = \mu \sin \beta$$.
As you are interested in the angle of refraction in the medium, the right answer is the first one $$\beta = \arcsin (\frac{\sin i}{\mu})$$.