Final answer:
The reflected ray goes along the same path as the incident ray in a mirror when the incident ray strikes the mirror perpendicular to its surface.
Step-by-step explanation:
The condition under which the reflected ray goes along the same path as the incident ray in a mirror is when the incident ray strikes the mirror perpendicular to its surface. This means that the angle of incidence is equal to 0 degrees. According to the law of reflection, the angle of reflection is also 0 degrees, resulting in the reflected ray traveling back along the same path as the incident ray.
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