Question

What are the critical angles for glass to air and water to air interface?

Answer 1

$$\begin{gathered} \mathrm{Critical}\mathrm{angle}\mathrm{for}\mathrm{glass}\mathrm{air}\mathrm{interface}: \\ \mathrm{\theta }={\sin }^{-1}\left(\frac{{\mathrm{n}}_{\mathrm{air}}}{{\mathrm{n}}_{\mathrm{glass}}}\right) \\ ={\sin }^{-1}\left(\frac{1.00}{1.5}\right) \\ =41.8^0 \\ \mathrm{Critical}\mathrm{angle}\mathrm{for}\mathrm{water}\mathrm{air}\mathrm{interface}: \\ \mathrm{\theta }={\sin }^{-1}\left(\frac{{\mathrm{n}}_{\mathrm{air}}}{{\mathrm{n}}_{\mathrm{water}}}\right) \\ ={\sin }^{-1}\left(\frac{1.00}{1.33}\right) \\ =48.7^0 \end{gathered}$$