Bi-Concave Lenses

Bi-Concave Lenses - Java Tutorial

This tutorial explores magnification by a simple bi-concave 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:

1 / f = 1 / p + 1 / q

where f is the focal length of the lens, p is the distance of the object with respect to the optical center of the lens, and q is the distance of the image to the optical center of the lens. The negatively curved surface of a bi-concave negative lens faces the object being imaged, and this results in a negative value for the focal length. In this instance, the lens equation yields a negative image distance resulting in the image being formed on the object side of the lens. As a result, the soldier is formed by an extrapolation of the light rays into a virtual image formed on the incoming-light side of the lens.