Question

What principle states that any ray of light subjected to reflection or refraction can be traced in reverse by a ray in the opposite direction?

Answer 1

The principle of reversibility of light.

Step-by-step explanation:

The principle of reversibility of light states that the path of a ray of light is reversible. If a ray of light, after suffering a number of reflections and/or diffractions, is allowed to fall normally on a mirror, it retraces its path along reverse direction.