question_answer

A right-angle prism is placed before an object in the two positions shown in Fig. The prism is made of crown glass with critical angle equal to\[\mathbf{41}{}^\circ \]. Trace the paths of two rays from P and Q normal to the hypotenuse in Fig. (a), and parallel to the hypotenuse in Fig. (b).                (a) (b)

Answer:

                As the angle of incidence inside the prism is greater than the critical angle\[\left( \text{41}{}^\circ  \right)\], the light rays suffer total internal reflection twice in case (a) and once in case (b). In both cases, inverted image \[P'Q'\] is formed, as shown in Fig. (a) and (b) respectively.