The focal length of a plano convex glass lens is 20 cm(μ_g=1.5) . The plane face of it is silvered. An illuminating object is placed at a dis†an ce of 60 cm
![Two identical plano - convex lenses can be combined in three ways, as shown. The ratio of the focal lengths of these combinations will be Two identical plano - convex lenses can be combined in three ways, as shown. The ratio of the focal lengths of these combinations will be](https://dwes9vv9u0550.cloudfront.net/images/4803840/ad468888-a328-4a12-85bf-d21b7546e5c9.jpg)
Two identical plano - convex lenses can be combined in three ways, as shown. The ratio of the focal lengths of these combinations will be
![Understanding Plano-Convex Lens Orientation and Focal Lengths - Getting Started with CO2 Lasers - Maker Forums Understanding Plano-Convex Lens Orientation and Focal Lengths - Getting Started with CO2 Lasers - Maker Forums](https://forum.makerforums.info/uploads/default/original/1X/55ee737787f39f3c4337e66766f875379d9c589b.gif)