Task id13133

Task id13133

A point light source is placed on the optical axis of a collecting lens with a focal length F1 = 30 cm at a distance a1 = 120 cm from it. On the other side of the lens, a diverging lens is placed in its focal plane. What is the focal length F2 of the diverging lens if the rays, after passing through the second lens, seem to come from the source itself?

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