A plane mirror of length 8 cm is moving with speed 3 m s⁻¹ towards a wall in situation as shown in figure. Size of spot formed on the wall is 32/x cm. Find the value of x.

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 2. Therefore the correct option is B.