Remember that when rays have to be converged back to find an apparent intersection, this will form a virtual image.
From Fig. 15.7, the similarities between a concave mirror and a convex lens become clear:
• As the object gets closer to the lens, the image gets further away. • All objects outside of F produce a real image from actual ray intersections. • All objects between F and the lens produce a virtual image from an apparent intersection of rays. This image is magnified and upright.
• As an object approaches 2F from outside, its image size increases. • When the object reaches 2F, its image is the same size. • As the object moves between 2F and F, its image continues to get bigger until the object reaches F, where the nature of the image changes to virtual.
