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JAMB Physics 2006 Question 35

Question 35

Light and Reflection

An object placed 10 cm from a concave mirror of focal length 5cm would have its image

  1. A.at infinity.
  2. B.10cm from the focus.
  3. C.at the centre of curvature.
  4. D.at the radius of curvature.
Show the answer and explanation

Answer: C (at the centre of curvature.)

Explanation

The radius of curvature is 2f = 10 cm, so the object is at the centre of curvature. 1/v = 1/5 − 1/10 = 1/10 gives v = 10 cm: the image is also at the centre of curvature.