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JAMB Physics 1982 Question 36

Question 36

Light and Reflection

Two mirrors of the same length are arranged as shown in the diagram (Fig. 10). A ray of light NO strikes the system at O and emerges along PQ. The emergent ray has been deviated through

Diagram for this question
  1. A.220°
  2. B.200°
  3. C.210°
  4. D.180°
  5. E.230°
Show the answer and explanation

Answer: D (180°)

Explanation

The mirrors are at right angles. Each reflection turns the ray, and for two mirrors at 90° the total deviation is always 360° − 2 × 90° = 180°: the ray comes back parallel to its original path.