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Posted April 12, 2005 7:00 AM

The question as it appears in the 04/12 edition of Specs & Techs from GlobalSpec:

Why is an image in a mirror inverted left-to-right but not top-to-bottom?

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Anonymous Poster
#1

Not sure

04/12/2005 8:49 AM

Obviously it has to do with the properties of the mirror - how it was designed. If you go in a fun house, you find mirrors that distort the returned image in all kinds of ways.

Participant

Join Date: Apr 2005
Posts: 2
#2

Here's looking at you!

04/12/2005 10:36 AM

No, it has to do with the properties of the head. Because my two eyes are displaced horizontally, the image is direct horizontally. If my eyes were displaced vertically, the direct (no inversion) would be from top to bottom.

Anonymous Poster
#3

The mirror question

04/12/2005 11:02 AM

Excellent explanation here: http://www.mathpages.com/home/kmath441.htm

The Architect

Join Date: Dec 2004
Location: GlobalSpec, Troy NY
Posts: 386
#5

Re:The mirror question

04/12/2005 3:56 PM

Whew! That's a long read (if you, unlike me, stick with it to the end).

I liked this "angle" (pun intended):
"From the context of the original question we can infer that it refers to the image in the mirror being reversed relative to the image we would see if we turned around and looked directly [behind us]. If so, then the answer depends on HOW we would turn around. Most likely we would rotate our field of view about a vertical axis, so the image we see will be reversed laterally (left-to-right). Of course, if we turn about a horizontal axis (difficult to do, but not impossible), the image we see would be reversed top-to-bottom."

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Mark Gaulin
Commentator

Join Date: Apr 2005
Posts: 71
#6

Re:The mirror question

04/13/2005 10:29 AM

Commentator

Join Date: Apr 2005
Posts: 71
#4

Re:Not sure

04/12/2005 12:51 PM

The answer is a "trick answer" (similar to a trick question); the real answer is that a mirror inverts images front-to-back.

Friend of CR4

Join Date: Dec 2004
Posts: 1776
#7

05/12/2005 2:56 PM

As reported in the 04/19 edition of Specs & Techs from GlobalSpec:

The image in a flat plane mirror is a virtual image — a type of image created by diverging light rays. While it may seem that a mirror reverses an image left-to-right, the image is actually reversed front-to-back. Its front and back are the opposite to you. For instance, if you write a word on a piece of paper and hold it up to a mirror, it appears as if the letters are reversed. But this is because you have actually rotated the piece of paper and are presenting it to the mirror reversed. It is the rotation which inverts the image, not the mirror.

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Off to take on other challenges. Good luck everybody! See you around the Interwebs.
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