Final answer:
The angle between the incident and the reflected rays, after being successively reflected by three mirrors at right angles, is 180 degrees due to the physics principle of the Law of Reflection.
Step-by-step explanation:
The concept you're dealing with here is the Law of Reflection, which pertains to the behavior of incident and reflected rays interacting with mirrors. The Law of Reflection stipulates that the angle of reflection equals the angle of incidence, both of which are observed relative to a perpendicular line to the mirror surface at the point the ray strikes the mirror.
When a ray of light reflects from two mirrors meeting at a right angle, the outgoing ray is parallel to the incoming ray. This means it has been effectively reflected twice. If we then add the third mirror at a right angle, it essentially performs a further 90 degrees rotation of the ray’s direction. This means the final ray is again parallel to the outgoing ray from the second mirror, consequently forming a total resultant angle of 180 degrees.
Therefore, the correct answer is a. 180ᵒ. The resultant ray, after three successive reflections by mirrors at right angles, has been turned half way around and hence the angle between the initial incident ray and the final reflected ray is 180 degrees.
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