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

$A$ thin prism of angle $15^o$ made of glass of refractive index $\mu_1 = 1.5$ is combined with another prism of glass of refractive index $\mu_2 = 1.75$. The combination of the prisms produces dispersion without deviation. The angle of the second prism should be ......$^o$

Assertion: There exist two angles of incidence for the same magnitude of deviation (except for minimum deviation) by a prism kept in air.
Reason: In a prism kept in air,a ray is incident on the first surface and emerges out of the second surface. If another ray is incident on the second surface along the path of the previous emergent ray,then this ray emerges out of the first surface along the path of the previous incident ray. This principle is called the principle of reversibility of light.

In the position of minimum deviation when a ray of yellow light passes through a prism,its angle of incidence is

For a transparent prism, if the angle of minimum deviation is equal to its refracting angle, the refractive index $n$ of the prism satisfies.

Two thin prisms of flint glass, with refracting angles of $6^o$ and $8^o$ respectively, possess dispersive powers in the ratio