a) Explain the phenomenon of the beam becoming broadens when a wide beam of parallel light enters the water at an angle, as illustrated in Figure 1. water Figure 1 (3 marks) b) Light from a sodium lamp passes through a 20 m tank of glycerin at a time t. If it takes time for to to travel over the same tank when filled with carbon disulfide, find the difference between to and t. [Given speed of light in a vacuum = 3 x 10" m.s", nyyear = 1.47, and nearbon swords = 1.63] (4 marks)