The refractive index of a medium is $\frac{3}{2}$. The speed of light in this medium is . . . . . . $ms^{-1}$. (Speed of light in vacuum is $c = 3 \times 10^{8} \,ms^{-1}$)

The refractive index of glass is $3/2$ and the refractive index of water is $4/3$. If the speed of light in glass is $2.00 \times 10^8 \ m/s$,the speed of light in water will be:

In the figure shown here,the angle made by the light ray with the normal in the medium of refractive index $\sqrt{3}$ is.......$^o$

$A$ bird is flying at $12 \ m$ height above the water surface and a fish is swimming $16 \ m$ below the water surface $(\mu_{\text{water}} = 4/3)$. Find the distance of the bird with respect to the fish as seen by the fish. (in $m$)

$A$ beam of light has a small wavelength spread $\delta \lambda$ about a central wavelength $\lambda$. The beam travels in vacuum until it enters a glass plate at an angle $\theta$ relative to the normal to the plate,as shown in the figure. The index of refraction of the glass is given by $n(\lambda)$. The angular spread $\delta \theta'$ of the refracted beam is given by

Optical phenomena taking place for a mirror and a lens respectively are . . . . . . and . . . . . . .