Images Formed by Curved Mirrors
We will focus our attention on three principal rays that are easy to follow and will also representative of the other rays involved in image formation.
We already know that an image is formed -- or something is "seen" -- when light rays diverge from a point. Here, light rays that originate at point O on the object strike a curved mirror and are reflected there so they converge to point I and then diverge from point I as they continue on their way. If our eyes detect these rays, we will see an image at point I. This is how an image is formed.
While this image is formed by all the rays that leave the object and strike the mirror, we will concentrate on three principal rays because they are easy to follow.
In fact, we will usually ignore all the other rays and locate an image by drawing only the principal rays.
The object distance do, the image distance di, and the mirror's focal length f are related by the image equation,
Be sure to note and remember the differences between real images and virtual images.
di > 0 for a real image.
di < 0 for a virtual image.
By "curved mirrors", we mean "spherical mirrors". However, it is also fun to look at the images formed by cylindrical mirrors.
(c) Doug Davis, 2002; all rights reserved
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