Principal Ray Diagram Simulation
This interactive animation is very similar to the one with the convex lens you have used before. Here, too, you can click on the object and drag it to different positions, so you can observe what happens to the image. But now, you are able to move the object not only up to the focal point, but even closer to the lens. Look what happens when the object passes the focal point! Suddenly, the real image is gone, and a virtual, enlarged image appears instead as soon as the object gets closer to the lens than the focal point. Again, since this is a virtual image, it is shown striped. Play with this animation until you feel you understand what happens. Make sure you are able to answer the questions: For what object distances does a convex lens produce a real image? For what object distances a virtual image?