Ray diagrams can be used to show the path light ... that is used to focus light. A convex lens is made from a transparent material that bulges outwards in the middle on both sides.

and when rays of light fall upon a lens, they are said to do so either directly or obliquely. No. 1 is a double convex lens, or two convex surfaces on the ono glass; No. 2 is a plano-convex lens ...

The transmitted light rays then form a real or virtual image of the object ... When referring to the image above, biconvex and plano-convex lenses are considered positive. Refraction of light through ...