You might have heard about inversion. But, what is a lateral inversion?
The word lateral is derived from the Latin word latus, which means side. Lateral inversion means sidewise inversion. It is the apparent inversion of left and right that occurs in a plane mirror.
Why do plane mirrors reverse left and right but they do not reverse up and down?
Well, the answer might be surprising. Mirrors do not reverse left and right, and they do not flip up and down. What mirrors do is they flip inside out.
Flipping of the image
Look at the arrows in the above image, which indicate the light ray from the object falling on the mirror. The arrow from the head of the object points to the top of the mirror, while the arrow from the feet points to the bottom. The left hand's arrow points to the left side of the mirror, while the right hand's arrow points to the right side of the mirror. There is no switching here, as you can see. It's a trick of the eye. As a result, the apparent lateral inversion we see is due to our perception rather than the mirror.
When an image is formed in a mirror, the left side of the object appears at the right side of the image and vice-versa. This is called a lateral inversion.
Reflection of candle light
Images showing lateral inversion
The distance between the object and the image from the mirror is always equal in the case of the plane mirror.