two plane mirrors placed making an angle theta. the incident ray on one mirror is parallel to another mirror & this ray after reflection from both the mirrors emerges parallel to the other mirror. find theta

Question

anonymous · Answer

90o angle is too big, the incoming ray reflects back on itself. Very small angles produce reflections going toward vertex. 45o angle looks right from sketch. Use incidence angle=reflection angle and see that this gives 90o between the two rays, thus parallel to each mirror.