- #1
jones123
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Homework Statement
An object is placed at 25 cm to the left of a diverging lens. A converging lens with a focal length of 12 cm is located 30 cm to the right of the diverging lens. The two-lenses-system forms a real inverted image 17 cm to the right of the converging lens (see attachment).
Homework Equations
What is the focal length of the diverging lens?
The Attempt at a Solution
I know that
1/f = 1/v - 1/b
For the converging lens I got:
1/12 = 1/v - 1/(-17) => v = 40.8 cm
For the diverging lens I got:
1/f = 1/40.8 - 1/(-30) => f = 17.29 cm
The correct answer should be -19 cm.
Thanks for the help!