Q.1. Find out, from Table, the medium having highest optical density. Also find the medium with lowest optical density.   

            Material medium       Refractive index

            Air                                     1.0003

            Ice                                     1.31

            Water                                1.33

            Alcohol                             1.36

            Kerosene                           1.44

            Fused quartz                     1.46

            Turpentine oil                    1.47

            Benzene                            1.50

            Crown glass                      1.52

            Canada Balsam                 1.53

            Rock salt                           1.54

            Carbon disulphide             1.63

            Dense flint glass                1.65

            Ruby                                 1.71

            Sapphire                            1.77

            Diamond                           2.42

(2 marks)

Q.2. You are given kerosene, turpentine and water. In which of these does the light travel fastest?

(Use the information given in Table above.)  

(2 marks)

Q.3.  Light strikes an interface between two materials of refractive indices n₁ and n₂, at an angle  to the normal to the surface. Show that a ray of the light is bent towards the normal if n₁ < n₂ and that a ray is bent away from the normal if n₁ > n₂.                                                                 

(2 marks)

Q.4.  A farsighted person has a near point located 350 cm from the eyes. Obtain the focal length of the converging lens used in contact lenses so that this person can read a book held 25 cm from the eyes.

(2 marks)

Q.5.  The diagram below shows the refracted ray BC through a concave lens and its foci marked as F₁ and F₂. Complete the diagram by drawing the corresponding incident ray.   

(2 marks)