An equilateral prism deviates a ray through $40^{\circ}$ for two angles of incidence differing by $20^{\circ}$. The possible angles of incidence are:

The refractive indices for the light of violet and red colours of any material are $1.66$ and $1.64$ respectively. If the angle of the prism made of this material is $10^o$,then the angular dispersion will be......$^o$.

Write the equation for the refractive index of a prism in terms of the angle of minimum deviation $(\delta_m)$ and the angle of the prism $(A)$.

$A$ 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:

In the visible region, the dispersive powers and the mean angular deviations for crown and flint glass prisms are $\omega, \omega^{\prime}$ and $d, d^{\prime}$ respectively. The condition for obtaining dispersion without deviation, when the two prisms are combined, is:

The angle of a prism made of a material of refractive index $\sqrt{2}$ is $90^{\circ}$. The angle of incidence for a light ray on the first face of the prism such that the light ray suffers total internal reflection at the second face is (in $^{\circ}$)