This applet illustrates image formation by a single lens. The user can vary the object distance.
To study the implications of the thin lens equation for paraxial rays, and to help understand image formation in simple lenses.
Target Student Population:
Secondary, Lower Level Undergrad
Prerequisite Knowledge or Skills:
Type of Material:
Java Applet, Simulation
Lecture demo, homework aid
Evaluation and Observation
The applet draws a bundle of rays that illustrate how to solve the thin lens equation graphically by highlighting the rays commonly use for graphical construction. The applet also gives numerical values for object and image distance that can be checked against the predictions of the thin lens equation.
Nice looking but very limited. Only the object distance can be changed. Distances are denoted by x in the applet and by d in the accompanying text. There are some spelling errors. In this applet, the inverse of the image distance is zero when the object distance is f.
Potential Effectiveness as a Teaching Tool
Good use of color. Object distance is easily changed, and the effect is immediate. The applet is effective in conveying the implications of the thin lens equation, i.e. under what circumstance are real or virtual images formed and how does the image distance behave as a function of the object distance.
Can't change f (although this is not a severe problem when used as a lecture/demo since instructor can discuss scaling). No discussion of magnification, or data to directly compute it.