Question

The diagram shows a point source P inside a water container. Four rays A, B, C, D starting from the source P are shown upto the water surface.
(ii) Show in the diagram the path of these rays after striking the water surface. The Critical Angle for water air surface is ${48}^o$.
(ii) Name the phenomenon which the rays B and D exhibit.

Answer 1

The path of each is ray is shown in the above diagram when they pass through the air-water interface.

(i) : Since the critical angle for water air surface is ${48}^o$. So the rays, for which angle of incidence is less than ${48}^o$, will get refracted at the surface i.e. A and B. While the ray for which angle of incidence is greater than ${48}^o$ will get total internally reflected i.e D.

Also, ray C has angle of incidence exactly as ${48}^o$. So it grazes over the water air interface.

(ii) : Ray B exhibits refraction while D exhibits total internal reflection.