Thin+Lens+Applet

SUMMARY of the APPLET The thin lens applet allows you to study the relationship between focal length and size of the image produced by either a lens or a mirror. The three essential rays from a ray diagram are shown at all times. The applet can be manipulated very easily. Not only can you select whether you want a lens or a mirror, you can also change the focal length and position of the lens, as well as the position and size of the object. As you make changes, the rays in the ray diagram also readjust themselves.

HINTS and SUGGESTIONS There is so much to do with this applet. Here are a few suggestions to get you started. If you really try to do these experiments, you will understand a lot more about lenses.
 * 1) Notice that a converging lens creates a real image of an object, but this image is upside down. Also, move the object around to see how the distance between the object and the lens affects the size of the image that has been created.
 * 2) Switch to a diverging lens (follow the instructions provided). Notice that the image produced is now a virtual image (in front of the lens) and that the image is right side up like the object. Move the position of the object to notice how the size of the image is affected by the distance between the object and the lens.
 * 3) Choose a concave mirror. Slide the object around. How close does the object have to be to the mirror in order for the image to be real (behind the mirror) and right side up? Where does the object need to be located to create a virtual (in front of the mirror), upside down image?

WHO CREATED THIS APPLET This applet was written a long time ago by Professor [|Fu-Kwun Hwang] at the National Taiwan Normal University in Taipei. A huge number of applets, including source code, are available at his website. Dr. Hwang's site is also part of the [|CoLoS project], which combines the efforts of teams around the world to help people learn the concepts of science by using the internet.