33099367A convex lens of focal length `25 cm` and a concave lens of focal length `20 cm`
Channel: Doubtnut
Date: 2020-01-26

A convex lens of focal length `25 cm` and a concave lens of focal length `20 cm` are mounted coaxially separated by a distance `d cm` . If the power of the combination is zero, `d` is equal to