Final answer:
The question involves using the Law of Reflection in Physics to demonstrate that a laser beam reflecting off two mirrors at right angles results in the outgoing ray being parallel to the incoming ray.
Step-by-step explanation:
The subject at hand is a Physics problem involving the Law of Reflection and concerns two plane mirrors set at a right angle to one another. This scenario is a classic example used to illustrate that when light (a laser beam, in this case) reflects off both mirrors, the outgoing ray ends up being parallel to the incoming ray. To show that the outgoing ray is parallel to the incoming ray, one would apply the Law of Reflection which states that the angle of incidence (the angle between the incident ray and the normal to the surface) equals the angle of reflection (the angle between the reflected ray and the normal).
In a setup where two mirrors are at right angles, the incoming ray reflects off the first mirror at an angle, and then reflects off the second mirror at the same angle but in the opposite direction. Because these two angles of reflection are equal, the path of the ray after reflecting off the second mirror is parallel to its original path before the first reflection. This holds true irrespective of the point of incidence along the first mirror.