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JAMB Physics 1982 Question 23

Question 23

Light and Reflection

In Fig. 3 an incident ray XY makes an angle of 15° with a fixed line AY which is normal to the surface of a plane mirror. If the mirror is turned as indicated by the arrow, through 40°, what angle will the reflected ray make with AY?

Diagram for this question
  1. A.25°
  2. B.40°
  3. C.15°
  4. D.55°
  5. E.95°
Show the answer and explanation

Answer: E (95°)

Explanation

Turning the mirror 40° turns its normal 40°, so the angle of incidence becomes 15° + 40° = 55°. The reflected ray is 55° on the other side of the new normal, which is 55° + 40° = 95° from AY.