Two thin lenses with focal lengths 23.0 cm and 33.0 cm are placed in contact in an orientation so that their optic axes coincide.What is the focal length of the two in combination? (Hint: A thin lens is one whose thickness is negligible).

Question

Quizplus · Accepted Answer

The focal length of two thin lenses in contact is given by the formula 1/f = 1/f1 + 1/f2, where f1 and f2 are the focal lengths of the individual lenses. In this case, we have f1 = 23.0 cm and f2 = 33.0 cm, so 1/f = 1/23.0 cm + 1/33.0 cm = 1/13.6 cm. Therefore, the focal length of the two lenses in combination is 13.6 cm.

Two Thin Lenses with Focal Lengths 23