The diameter of a plano convex lens is `6 cm` and thickness at the centre is `3 mm`.
Channel: Doubtnut
Date: 2020-08-02

The diameter of a plano convex lens is `6 cm` and thickness at the centre is `3 mm`. If the speed of light in the material of the lens is `2 xx 10^8 m//s`, what is the focal length of the lens ?