An image in a convex lens is upright and magnified 3 times. If the focal…

Physics JAMB 2011

An image in a convex lens is upright and magnified 3 times. If the focal length of the lens is 15 cm, what is the object distance?

  • 10 cm checkmark
  • 25 cm
  • 16 cm
  • 14 cm

The correct answer is: A

Explanation

m = v/u = -3
v = -3u
f = 15cm
1/v + 1/U = 1/f
1/-3U + 1/u = 1/15
2/3u = 1/15
3U = 15 x 2
U = 30/3
= 10 cm

There is an explanation video available .

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