We've all seen the message, shown above, written on the rear-view mirror of cars. The mirror is a convex mirror, which makes images appear smaller, or further away, then they actually are. Some mirrors, such as those in your bathroom, display accurately sized images, while others create images that are larger or smaller than reality. Lenses can be used to magnify or reduce images also. This chapter will introduce you to convex and concave mirrors, lenses, and the properties of each.
As light rays reflect off of mirrors and pass through lenses, they create images of the object emitting or reflecting the light. In plane mirrors, the images are reversed left-to-right, though they remain upright. In curved mirrors and lenses, the interactions between objects and their images are more complex. Convex and concave lenses and mirrors can cause images to be diminished or enlarged, upright or inverted, and real or virtual.