Reflect on this! If you look into a plane mirror and wink your right eye, your
image winks its left eye! The image of your right hand will have the symmetry
of a left hand (Figure 1). We say the image is laterally inverted.
If you look straight into a pair of mirrors arranged at a right angle (Figure 2), and wink your right eye, your image will also wink its right eye. The image of your right hand will have the symmetry of your right hand. In other words, you see
yourself as others see you.
Why is there a difference? When you look at your image in a pair of mirrors at
90o, the image you see is formed by light that has been reflected not once, but
twice. One might say the double reflection produces a laterally inverted
image of a laterally inverted image.
You may notice that you see more than one image when you look at yourself in
the mirror pair. How many images are there? Do they all look the same?
What happens if you use different angles between the mirrors?