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JAMB Physics 1992 Question 26

Question 26

Light and Reflection

A concave mirror has a radius of curvature of 36cm. At what distance from the mirror should an object be placed to give a real image three times the size of the object?

  1. A.12cm
  2. B.24cm
  3. C.48cm
  4. D.108cm
Show the answer and explanation

Answer: B (24cm)

Explanation

f = 36/2 = 18 cm and v = 3u. 1/u + 1/(3u) = 1/18 gives 4/(3u) = 1/18, so u = 24 cm.