Two plane mirrors are placed perpendicular to each other. A ray strikes at 45° to one mirror and after reflection from the second mirror will be :-
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Question

Two plane mirrors are placed perpendicular to each other. A ray strikes at 45° to one mirror and after reflection from the second mirror will be :-

G1 Physics · Accepted Answer

Derived solution: Step 1: Use the law of reflection i = r and plane-mirror symmetry. The image is as far behind the mirror as the object is in front; rotation of a mirror by φ rotates the reflected ray by 2φ. Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is parallel to the original ray. Therefore the correct option is B.