Why do mirrors reflect left and right and not up and down?

Answer 1

I'm guessing this questioner meant "Why do mirrors reverse, etc."

That's the well known phenomenon of "lateral inversion" of the image in a flat

mirror.

This is the basic explanation:

1) The mirror reverses the object in the direction perpendicular to the surface of the mirror. That's all it does. The mirror has no effect on left and right or on up and down.

2) However, we usually find it hard to notice this "front to back" inversion. That results in us "seeing" the image as reversed from left to right.

Answer 2

This is because light travels in straight lines (usually) and the angle at which a light ray is reflected equals the angle at which the light ray hits the mirror.

When you draw a diagram, using these facts, you find that a "virtual image" is formed behind the mirror. The distance in front of the mirror of a point on the object is equal to its distance behind the mirror, in the image.

So, you have an image of the object that is reversed in the direction perpendicular to the mirror surface.

Answer 3

Quite simply it is because a mirror isn't reversing what you are looking at. You are just seeing you from the perspective of someone looking at you (You have essentially cloned yourself visually).

That's why when you get close and kiss a mirror all your body parts touch the mirror appropriately ;).

Unless we want to try and argue that everyone we are looking at are reverse images of themselves?

I hope that helps.

If not just think of it this way, you are cloning yourself looking at yourself, so why wouldn't you look like you do? People don't look upside down when they stand in front of you so why would your reflection?