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

$A$ prism of refracting angle $60^\circ$ is made with a material of refractive index $\mu$. For a certain wavelength of light,the angle of minimum deviation is $30^\circ$. For this wavelength,the value of the refractive index of the material is:

In an equilateral prism,the ray undergoes minimum deviation when it is incident at an angle of $50^{\circ}$. The angle of minimum deviation is (in $^{\circ}$)

The respective angles of the flint and crown glass prisms are $A'$ and $A$. They are to be used for dispersion without deviation. The ratio of their angles $A'/A$ will be:

The angle of deviation through a prism is minimum when
$(A)$ Incident ray and emergent ray are symmetric to the prism
$(B)$ The refracted ray inside the prism becomes parallel to its base
$(C)$ Angle of incidence is equal to that of the angle of emergence
$(D)$ When angle of emergence is double the angle of incidence
Choose the correct answer from the options given below

The graph between angle of deviation $(\delta)$ and angle of incidence $(i)$ for a triangular prism is represented by :-