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Ray Optics: Mirror — Rotation Effect MCQ

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Mirror — Rotation EffectHardQuestion 20205

Question

When a plane mirror is rotated by angle θ, the reflected beam rotates by:
  1. A
    θ
  2. B
    2θ
    Correct
  3. C
    θ/2
  4. D
    4θ

Correct answer

2θ

Explanation

When a mirror rotates by θ, the normal also rotates by θ. The new angle of incidence changes by θ, and the new angle of reflection changes by θ. The net rotation of the reflected beam = 2θ. Used in galvanometers and laser scanning.

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