A glass slab of width $t$ and refractive index$\mu$ is placed as shown in the figure. If the point object moves with a speed $2 \mathrm{cm} {\mathrm{s}}^{-1}$ towards the slab then the speed of image observed will be

    

A medium shows relation between $i$ and $r$ as shown. If speed of light in the medium is $\left(nc\right)$, then value of $n$ is 

Find the displacement of the ray after it emerges out from $CD$.

Given the velocity of light in quartz$=1.5\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1}$ and velocity of light in glycerine $\left(\frac{9}{4}\right)\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1}$. Now a slab made of quartz is placed in glycerine as shown. What is the shift produced by slab?

A ray $R_1$ is incident on the plane surface of the glass slab (kept in air) of refractive index $\sqrt{2}$ at an angle of incidence equal to the critical angle for this air-glass system. The refracted ray $R_2$ undergoes partial reflection and refraction at the other surface. The angle between the reflected ray $R_3$ and the refracted ray $R_4$ at that surface is