$A$ bird is looking at a fish underwater from the air. $h_1$ is the height of the bird above the water surface and $h_2$ is the depth of the fish below the water surface. If $\mu$ is the refractive index of water with respect to air,then the distance of the fish as observed by the bird is:

The time taken by sunlight to cross a $5 \,mm$ thick glass plate $(\mu = 3/2)$ is

Three immiscible transparent liquids with uniform refractive indices $\frac{3}{2}, \frac{4}{3}$ and $\frac{6}{5}$ are arranged one on top of another. The depths of the liquids are $3 \ cm, 4 \ cm$ and $6 \ cm$ respectively. The apparent depth of the vessel is (in $cm$)

$A$ glass beaker is filled with water up to $5 \,cm$. It is kept on top of a $2 \,cm$ thick glass slab. When a coin at the bottom of the glass slab is viewed at normal incidence from above the beaker,its apparent depth from the water surface is $d \,cm$. The value of $d$ is close to ........ $cm$ (the refractive indices of water and glass are $1.33$ and $1.5$,respectively).

$A$ coin is placed at the bottom of a glass slab of refractive index $3$ and thickness $x$. Another glass slab of refractive index $\mu$ and thickness $x$ is placed on top of it. If the coin appears to be at the interface of the two slabs,then $\mu = $ . . . . . .

An air bubble in a glass slab with refractive index $1.5$ (near normal incidence) is $5\, cm$ deep when viewed from one surface and $3\, cm$ deep when viewed from the opposite face. The thickness (in $cm$) of the slab is