If one places a perpendicular mirror at the end of a laser beam passing through several materials at different angles, what happens?
Answer a. At refraction points it bends the other way and leaves the path.
b. The light retraces its path exactly in reverse.
c. At reflection points it bends the other way and leaves the path.
d. It depends on the path
There exists the Principle ofReversibility that argues that the ray retraces the path exactly (that is assuming the refractive and reflecting elements are ideal and do not distort the angles, which is in reality true only to an extent). Answer: b