An object 5.0 cm high is placed 2.0 cm from a converging (convex) lens which is being used as a magnifying glass. The image produced is 6.0 cm from the lens and is 15 cm high.What is the focal length of the lens?

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1 Answer
Mar 13, 2018

1.5cm1.5cm

Explanation:

We don't need the height of the object or image here.

From thin lens formula :-
1/f=1/d_i+1/d_o1f=1di+1do

=>1/f=1/6+1/21f=16+12

LCM of 2 and 6 = 6

=>1/f=1/6+3/61f=16+36

=>1/f=(1+3)/61f=1+36

=>1/f=(4)/61f=46

=>f=6/4f=64

Flipping both sides,
=>f=3/2f=32

=>f=1.5cmf=1.5cm