Two converging lenses, the first with focal length 25 cm and the second with focal length 20 cm, are separated by 30 cm. A 4.0 cm tall object is placed 50 cm in front of the first lens. Which of the following characteristics does the final image have?
A) real and upright
B) real and inverted
C) virtual and upright
D) virtual and inverted
E) none of these choices are correct

Question

Quizplus · Accepted Answer

The first lens produces a real inverted image of the object at a distance of 25 cm. This image then acts as the object for the second lens.

Using the thin lens formula: 1/f = 1/di + 1/do, where f is the focal length, di is the image distance, and do is the object distance, we can find that the image distance for the second lens is di = -40 cm.

The negative sign indicates that the image is real and inverted. Therefore, the final image is real and inverted, making choice B the correct answer.

Two Converging Lenses, the First with Focal Length 25 Cm