A prism of refractive index 2 has refracting angle of 60^ . At what angle a ray must be incident one it so that it suffers a minimum deviation?

Step-by-step solution

In the position of minimum deviation angle of incidence is equal to angle of emergence. Let a ray of monochromatic light P Q be incident on face A B . P Q R S is path of light ray, where i is angle of incidence r angle of refraction, r angle of incidence and i angle of emergence. In position of minimum deviation i^ =i, r^ =r, = m2 r=A or r= A 2 Given A=60^ , r= 60^ 2 =30^ Also from Snell's law = i r = i 30^ 2 = i 30^ i= 2 1 2 = 1 2 i=45^