This animation is very similar to the previous one. It allows you to explore Snell's law again, only now you can shine the laser beam from any direction you like. You are free to select the media for the upper and lower part of space from the drop-dow . . .

The eye is basically a hollow globe with a radius of a little less than an inch that is covered with a tough white coating, the sclera. Light rays entering the eye first go through the cornea, a transparent tissue, and the anterior chamber which is fi . . .

This is a collection of three animations detailing the concept of the magnifying glass.

Let's now construct the principal ray diagram for a concave, i.e., a diverging lens. The idea is the same as for the convex lens: we will consider how the three particular rays for which we know what happens are refracted by the concave lens: The ray . . .

We know that not only a plane mirror produces an image of an object in front of it – a convex spherical mirror does, too! Just look at the back of a metal spoon if you don't believe it! This interactive animation shows you how such an image arises, an . . .

Here you can see what is called a principal ray diagram. We have constructed the image of the candle from the three principal rays, as we explained before. This interactive animation allows you now to move the object relative to the lens, and to obser . . .

This cartoon shows you a marching band, walking from an area of solid ground where the musicians can walk fast, into a region of muddy ground where they have to walk more slowly. Each row of musicians carries a long pole. Watch what happens when the f . . .

In this interactive animation, you can explore how the lens of the eye adjusts its thickness. This allows you to see an object in focus as it is moved to different distances from the lens. Drag the object to another position and observe how the lens c . . .

We have seen in the last video that a convex lens indeed makes an image of our object, the little lit arrow. But how exactly is this image formed? This animation shows you that light rays are going off in all directions from every point of the object. . . .

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 . . .