The figure below shows light in air incident on the side of a rectangular glass block at an angle of 60 glass block 60 X The refractive index of the glass is 1.6. The light travels in the glass and is incident on side XY at P (a) State two aspects of the light wave which changes when it leaves the air and enters the glass. [2 mks] (b) At the point where the light enters the glass, the angle of refraction is r. Calculate angle r [2 mks] (c) (i) Calculate the critical angle c for light travelling in the block [2 mks] (li) At P the angle 0 between the ray and the normal is given by e - 90 - r State and explain what happens to the light when it is incident on side XY [2 mks] (d) Give two differences between light waves and sound waves [2 mks]