Two converging lenses are separated by 23.40 cm. The focal length of each lens is 12.20 cm. An object is placed 35.00 cm to the left of the lens that is on the left. Determine the final image distance relative to the lens on the right.

Answer 1

The image formed by the first lens acts as the object for the second lens. For the location of the first lens image,
1/di = 1/f - 1/do = 1/12.2 - 1/35 = 0.0534
do = 18.73 cm. That places it 4.67 cm in front of the second lens.

For the second lens,
1/4.67 + 1/di = 1/12.2
di = -7.57 cm
The final image is 7.57 cm to the left of the second lens, in the region between the lenses.