When light of wavelength $\lambda$ is incident on an equilateral prism kept in its minimum deviation position,it is found that the angle of deviation equals the angle of the prism itself. The refractive index of the material of the prism for the wavelength $\lambda$ is,then

$A$ ray of light suffers minimum deviation when incident on a prism having an angle of the prism equal to $60^{\circ}$. The refractive index of the prism material is $\sqrt{2}$. The angle of incidence (in degrees) is . . . . . . .

$A$ prism is made of glass of unknown refractive index. $A$ parallel beam of light is incident on a face of the prism. The angle of minimum deviation is measured to be $40^{\circ}$. What is the refractive index of the material of the prism? The refracting angle of the prism is $60^{\circ}$. If the prism is placed in water (refractive index $1.33$),predict the new angle of minimum deviation of a parallel beam of light.

$A$ deviation of $2^{\circ}$ is produced in the yellow ray when prisms of crown and flint glass are achromatically combined. Taking dispersive powers of crown and flint glass as $0.02$ and $0.03$ respectively and refractive indices for yellow light for these glasses as $1.5$ and $1.6$ respectively,the refracting angle for the crown glass prism will be $........\,^{\circ}$ (in degrees) (Round off to the nearest integer).

The angle of a prism is $A$ and its refractive index is $\cot \frac{A}{2}$. The angle of minimum deviation is:

$A$ prism of refractive index $\sqrt{2}$ and refracting angle $A$ produces a minimum deviation $D_m$. $A$ ray incident on one face at an angle of incidence $i = 45^{\circ}$ undergoes minimum deviation. The values of $A$ and $D_m$ are respectively: