Question

Two identical thin isosceles prisms of refracting angle A and refractive index `mu` are placed with their bases touching each other and this system can collectively act as a crude converging lens. A parallel beam of light is incident on this system as shown in Figure. Find the focal length of this so called converging lens.

Answer 1

Since `tan delta=(h)/(f) rArr f=(h)/(tan delta)`
Further, `delta =(mu-1)A rArr f=(h)/((mu-1)A)`