A small object is 25.0 cm from a diverging lens as shown in the figure . A converging lens with a focal length of 11.4 cm is 30.0cm to the right of the diverging lens. The two-lens system forms a real inverted image 17.0 cm to the right of the converging lens.
The Attempt at a Solution
1/f = 1/o + 1/i at every step
1/12 = 1/o + 1/17.0
o = 40.8
This means the second object, which is the first image, was 40.8 cm to the left of the conv lens.
This means the second object was 40.8 - 30 = 10.8 cm to the left of the div lens
So the image distance for the div lens is -10.8 and
1/f = 1/25.0 + 1/(-10.8)
1/f = 0.04 - 0.0926 = -0.05259
f = -19.0 cm is the focal length of the div lens