A fish is rising up vertically inside a pond with velocity $4 \mathrm{cm} {\mathrm{s}}^{-1}$ and notices a bird which is diving vertically downward along the same vertical line as that of fish and its velocity appears to be $16 \mathrm{cm} {\mathrm{s}}^{-1}$ (to the fish). What is the real velocity of the diving bird, if refractive index of water is $4/3$?

Find the apparent depth of the object seen by observer $A$ (in the figure shown)

At what values of the refractive index of a rectangular prism can a ray travel as shown in the figure. The section of the prism is an isosceles triangle and the ray is normally incident onto the face $AC$.

Find the angle of deviation suffered by the light ray shown in figure for following two conditions The refractive index for the prism material is $\mu =3/2$.

(i) When the prism is placed in air $(\mathrm{\mu }=1)$

(ii) When the prism is placed in water $(\mathrm{\mu }=4/3)$