When a glass prism of refracting angle $60^{\circ}$ is immersed in a liquid, its angle of minimum deviation is $30^{\circ}$. The critical angle of glass with respect to the liquid medium is (in $^{\circ}$)

The refracting angle of a prism is $A,$ and the refractive index of the material of the prism is $\cot(A/2).$ The angle of minimum deviation is:

$A$ plot between the angle of deviation and angle of incidence is shown in the figure. From the graph,one can say that the prism angle is ....... (in $^{\circ}$)

$A$ prism of refractive index $n_{1}$ and another prism of refractive index $n_{2}$ are stuck together (as shown in the figure). $n_{1}$ and $n_{2}$ depend on $\lambda$, the wavelength of light, according to the relation:
${n}_{1}=1.2+\frac{10.8 \times 10^{-14}}{\lambda^{2}} \text{ and } {n}_{2}=1.45+\frac{1.8 \times 10^{-14}}{\lambda^{2}}$
The wavelength for which rays incident at any angle on the interface $BC$ pass through without bending at that interface will be $....\,nm.$

$A$ parallel beam of light is incident on a thin prism with a prism angle of $\frac{4}{\pi}$ degrees. The refractive index of the prism is $1.5$. The focal length of the lens is $60 \ cm$. The coordinates of the converging point of the beam are:

$A$ ray of light is incident on the first face of an equilateral glass prism at an angle of incidence '$i$'. The emergent ray just grazes along the adjacent face. The refractive index of the prism is $\sqrt{2}$. The value of the angle of incidence at the first face is $(\sin 45^{\circ} = 1/\sqrt{2}, \sin 90^{\circ} = 1)$.