Draw a diagram to show how an image is produced by a pair of total reflecting prisms arranged as in a periscope.

State the laws of refraction. Distinguish between absolute refractive index and refractive index of a medium. Show that $n=\raisebox{1ex}{$c$}\!\left/ \!\raisebox{-1ex}{$v$}\right.$, where letters have usual meanings.

Explain why does a swimming pool appears shallower than it actually is. Obtain an expression for the normal displacement of an object immersed in water.

Explain, with ray-diagram, total internal reflection of light. Give two conditions for it to take place. Obtain relation between critical angle and refractive index of the denser medium.

Show, by a ray-diagram, how a totally reflecting glass prism can be used to deviate a ray through $90°$.

Show, by ray-diagram, how a totally reflecting glass prism can be used to deviate a ray through $180°$.

Explain the refraction of light, write its laws and also write the basic cause of refraction of light. Derive the relation $n=\frac{\text{ Real depth }}{\text{ Apparent depth }}$.