A converging lens produces an image four times as large as an object placed 25cm from the lens. Calculate its focal length.

By: |Published on: May 21|Categories: Physics WAEC| 0 comments

A. 100cm
B. 33cm
C. 29cm
D. 20cm

Correct Answer: Option D

D. 20cm

Explanation

M = v/u

v = mu = 4 x 25 = 100m

1/v+1/u=1/f

1/100+1/25=1/f

f = 20cm

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