Two plane mirror MN and PQ inclined at an angle θ as shown in figure. O is a point source 10 cm above the mirror MN. For light rays striking on the mirror MN directly from O not to strike the mirror PQ, the maximum value of θ is :-

Question

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 60°. Therefore the correct option is C.