Задача id12552

A converging beam of rays falls on a thin diverging lens in such a way that the extensions of all rays intersect at a point lying on the optical axis of the lens at a distance a = 15 cm from it. Find the focal length of the lens if, after refraction in the lens, the rays are collected at a point located behind the lens at a distance b = 60 cm from the lens.

Detailed solution. Format gif