Cylindrical Mirror

When you look into a cylindrical mirror with the axis of the mirror horizontal and with your face a foot or more away from the mirror, your image is upside-down. That's because the light from your hair bounces off the curved mirror and comes to your eye from below. To make sense of the angle at which the light is entering your eye, your eye and brain must see the image of your face as upside-down and a little bit in front of the mirror. As everyone knows, a flat mirror reverses your right side and your left side. How does it do that? Suppose you are standing face to face with another person. If your right ear points toward the east, his or her left ear will point toward the east. Now, instead of facing another person, suppose you are facing a flat mirror with your right ear pointing to the east. The light from your right ear will bounce off the flat mirror and enter your eyes from the east. Even though your east ear is the east ear of the image, your right ear has become the left ear of the image! (Yes, this is a little mind boggling at first reading. But once you get it, it will seem simple.)