angle of minimum deviation

Question

A hollow prism is made of plane parallel plates of glass. The angle between the faces is 56°. What is the angle of minimum deviation when the prism is filled with carbon disulphide and sodium D line having wavelength of 589 μm is passed through it. {n(carbon disulphide)=1.63}

Answer 1

Deviation produced is given by

Angle of deviation = A( refractive index -1)

The deviation angle is minimum when Angle of incidence and angle of emergence from prism are equal