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JAMB Physics 1978 Question 42

Question 42

Lenses and Optical Instruments

An object 1 cm high placed on the axis 15 cm from a converging lens forms an image 30 cm from the lens. The size of the image is

  1. A.0.5 cm
  2. B.1.5 cm
  3. C.3 cm
  4. D.2.5 cm
  5. E.2 cm.
Show the answer and explanation

Answer: E (2 cm.)

Explanation

Magnification = v/u = 30/15 = 2, so the image is 2 × 1 cm = 2 cm high.