The Plano-Convex Lens

This tutorial explores magnification by a simple plano-convex lens when the object faces the flat surface of the lens. To operate the tutorial, place your mouse cursor on the soldier, then click on the left-hand button and move him back and forth to view different levels of magnification.

For the purposes of this tutorial, we apply the following equation to describe lens action:

where f is the focal length of the lens, p is the distance of the distance with respect to the optical center of the lens, and q is the distance of the image to the optical center of the lens.

This tutorial examines what happens to the "real" image of an object as it is moved closer to a simple plano-convex lens when the object faces the flat surface of the lens. At points greater than two times the focal length of the lens, the image of an object is real, inverted, and smaller than the object. At two times the focal length, the image is the same size as the object and is real and inverted. At less than two times the focal length, the image is real, inverted, and magnified. When the object approaches closer than the focal length of the plano-convex lens, it appears to be on the same side of the lens as the object, 25 centimeters from the eye, and it is magnified and is now a virtual image.