Find the focal length of the glass lens in the figure? Please help?

imgur.com/VTrRX

Answer 1

The figure shows that the radius of curvatures of the two lens surfaces are each 40 cm.
The focal length is half the radius of curvature.

R = 40 cm
FL = R/2 = 20 cm.

Hope this helps,

-Guru

Answer 2

Actually the correct answer is 40 cm. Take those two arrows and slide them along the lens, you’ll see that they both touch at the x-axis.

Source(s): I just did it on MasteringPhysics…

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