Two plane mirrors are inclined at 70°. A ray incident on one mirror at angle, after reflection falls on the second mirror and is reflected from there parallel to the first mirror. is
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Question

Two plane mirrors are inclined at 70°. A ray incident on one mirror at angle, after reflection falls on the second mirror and is reflected from there parallel to the first mirror. is

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 50°. Therefore the correct option is A.