Two identical thin planoconvex glass lenses (refractive index `1.5)` each having radius of c
Channel: Doubtnut
Date: 2020-01-19

Two identical thin planoconvex glass lenses (refractive index `1.5)` each having radius of curvature of `20cm` are placed with their convex surfaces in contact at the centre. The intervening space is filled with oil of refractive index `1.7`. The focal length of the combination is