A circular beam of light of diameter d=2 cm falls on a plane surface of glass. The angle of incidence is 60° and refractive index of glass is μ=3/2. The diameter of the refracted beam is

Let d' be the diameter of refracted beam.Then, d=PQcos⁡60∘and d ' = PQ cos ri.e. d′d=cos⁡rcos⁡60∘=2cos⁡ror d′=2dcos⁡r    sin⁡r=sin⁡iμ=3/23/2=13∴     cos⁡r=1−sin2⁡r=23∴     d′=(2)(2)23=423cm≈3.26cm