If a convex lens of focal length 12cm is used to produce a real image four times the size of the object, how far from the lens must the object be placed?

By: |Published on: Nov 10|Categories: Physics JAMB| 0 comments

A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm

Correct Answer:

Option B = 15 cm

Explanation

Magnifications = V/U = 4
∴ V = 4U
1/V + 1/U = 1/f
1/4u + 1/U = 1/12
5/4U = 1/12
4U = 12 x 5 = 60
∴ U = 15 cm

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