In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.

In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.

Sir Isaac Newton once wrote, in what must be one of the most oft-quoted lines in the history of science ... he discovered that plano-convex and plano-concave lenses worked best—that is ...

When referring to the image above, biconvex and plano-convex lenses are considered positive. Refraction of light through a converging lens. Image credit: Science Learning Hub Negative lenses cause a ...