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JAMB Physics 2010 Question 29

Question 29

Light and Reflection

An object 4cm high is placed 15cm from a concave mirror of local length 5cm. The size of the image is

  1. A.3cm.
  2. B.5cm.
  3. C.4cm.
  4. D.2cm.
Show the answer and explanation

Answer: D (2cm.)

Explanation

1/v = 1/5 − 1/15 = 2/15, so v = 7.5 cm. Image height = object height × v/u = 4 × 7.5/15 = 2 cm.