Draw diagrams to illustrate the total internal reflection.

State whether the following statement is true or false:

If the angle of incidence is greater than the critical angle, light is not refracted at all, when it falls on the surface from a denser medium to a rarer medium.

The refractive index of air with respect to glass is expressed as

${}_g{\mu }_a=\frac{\sin i}{\sin r}$.

Write down a similar expression for ${}_a{\mu }_g$ in terms of the angles $i$ and $r$.

The refractive index of air with respect to glass is expressed as ${}_{\mathrm{g}}\mathrm{\mu }_{\mathrm{a}}= \frac{\sin \mathrm{i}}{\sin \mathrm{r}}$ . If angle r is given as$90°$, then find that what the corresponding angle$\mathrm{i}$called and it will be equal to what?

The given figure shows a point source P inside a water container three rays A, B and C starting from the source P are shown up to the water surface. Show in the diagram the path of these rays after striking the water. The critical angle for water-air surface is $48°$. 

The given figure shows a point source P inside a water container three rays A, B and C starting from the source P are shown up to the water surface. Name the phenomenon which the rays A, B and C exhibit.

In the given figure PQ and PR are the two light rays emerging from an object P. The ray PQ is refracted as QS. State the special name given to the angle of incidence $\angle \mathrm{PQN}$of the ray PQ.

In the given figure below PQ and PR are the two light rays emerging from an object P. The ray PQ is refracted as QS. What is the angle of refraction for the refracted ray QS?