$A$ thin prism $P_1$ with angle $6^o$ and made from glass of refractive index $1.54$ is combined with another thin prism $P_2$ of refractive index $1.72$ to produce dispersion without deviation. The angle of prism $P_2$ will be:

$A$ deviation of $5^o$ is observed from a prism whose angle is small and whose refractive index is $1.5$. The angle of the prism is.......$^o$

The principal section of a glass prism is an isosceles triangle $ABC$ with $AB = AC$. The face $AC$ is silvered. $A$ ray of light is incident normally on the face $AB$ and after two reflections, it emerges from the base $BC$ perpendicular to the base. The angle $BAC$ of the prism 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 $....\,nm.$

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

$A$ thin prism $P_1$ with angle $4^{\circ}$ made of glass having refractive index $1.54$ is combined with another thin prism $P_2$ made of glass having refractive index $1.72$ to produce dispersion without deviation. The angle of the prism $P_2$ in degrees is: