How To Draw Ray Diagrams. The three principal rays which are used for visualizing the image location and size are: When you draw ray diagrams on the board or on a transparency:
The description is applied to the task of drawing a ray diagram for an object located beyond the 2f point of a double convex lens. The image formed by a single lens can be located and sized with three principal rays. This is sometimes referred to as “the two rules of refraction for diverging lenses”.