Angle of deviation $(\delta)$ by a prism (refractive index = $\mu$ and supposing the angle of prism $A$ to be small) can be given by

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 $^{\circ}$)

For an equilateral prism,it is observed that when a ray strikes grazingly at one face,it emerges grazingly at the other. Its refractive index will be

The minimum deviation produced by a hollow prism filled with a certain liquid is found to be $30^{\circ}$. The light ray is also found to be refracted at an angle of $30^{\circ}$. Then the refractive index of the liquid is

The angle of minimum deviation is equal to the angle of the equilateral prism. At what angle of incidence $i$ will this minimum deviation occur?

For flint and crown glass prisms,the prism angles are $A'$ and $A$ respectively. When they are used to produce dispersion without deviation,the ratio $A'/A$ will be: