question_answer

A ray of light passes through four transparent media with refractive indices \[{{\mu }_{1}},\,\,{{\mu }_{2}},\,\,{{\mu }_{3}}\] and \[{{\mu }_{4}}\] as shown in the figure. The surfaces of all media are parallel. If the emergent ray CD is parallel to the incident ray AB, we must have

A) \[{{\mu }_{1}}={{\mu }_{2}}\]

B) \[{{\mu }_{2}}={{\mu }_{3}}\]

C) \[{{\mu }_{3}}={{\mu }_{4}}\,\]

D) \[{{\mu }_{4}}={{\mu }_{1}}\,\]