Mirror Trivia Question

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Happy Holidays to all.
Here is a little mirror trivia to think about.

Lets say your standing 5 ft from a large mirror.
You see the image size of yourself as;
Question: Other people would see you from a distance of 5 ft OR 10 ft ? ? ?

Please answer and explain.

I say if your standing 5 ft from a mirror, your 'image size' would be the same as someone seeing you from a distance of 10 ft.
I can't find the words to explain.
 
Originally Posted By: MasterSolenoid

I say if your standing 5 ft from a mirror, your 'image size' would be the same as someone seeing you from a distance of 10 ft.
I can't find the words to explain.


It's 2X the visual depth.
 
I've never thought about this before and I have no idea if I am correct but.....

The light emitted from your body at a distance of 5 feet would be directly reflected back at you from that distance, so the mirror does reflect your image's appearance from 5 feet. Since we have binocular vision, when we focus on a single point, the light converges to a single point. The further the object is away from us, the light converges more gradually and appears to a finer (smaller) point.

However when an object is reflected, that convergence is reversed. The light from an object flips from one side to the other since our eyes are side-by-side. (I believe if our eyes were oriented vertically instead of horizontally, mirrors would display images upside down rather than reversed side to side). So rather than converging, the light diverges once it is reflected and expands again to the viewing point.

The fact that we don't see out of the center of our bodies has an effect too. Our feet appear further than our eyes do because of how far that light must travel before our eyes collect it.
 
The term you’re looking for is apparent size.

If you’re 5 feet from the mirror, you’ll see yourself at the apparent size as viewed from ten feet.
 
Also the minimum size of the mirror required to see your entire body at once is half of your actual height and width. This is true no matter how far away you are from the mirror.
 
Here's an experiment I was told to try when I first took up photography and had my first SLR. I went to the bathroom mirror, stuck a piece of paper on it, focused on this(manual focus, but it will work with any type of passive AF camera) and noted the distance. I then focused on the image of myself in the mirror and noted the distance. It was indeed twice that of the mirror itself.

So, I'll go with the image to someone else appears as if you're standing twice the actual distance from the mirror.
 
In that case I retract my initial explanation of nonsensical whimsy.
happy2.gif


and here is a simple graphic to explain it:

slide_2.jpg
 
Better mirror trivia is the first use of a rear view mirror on a car was by Ray Harroun on the 1911 Indianapolis 500 winning Marmom Wasp. Every other car had a ride on mechanic to tell the driver about any cars coming up behind.
 
I have a better one... it's been used for new engineer interviews.

When you look at a mirror, why does the image flip left-to-right, but not top-to-bottom?
 
Originally Posted By: Kestas
I have a better one... it's been used for new engineer interviews.

When you look at a mirror, why does the image flip left-to-right, but not top-to-bottom?

That's a trick question which my high school physics teacher once asked our class
wink.gif
 
I'll take a stab at it.

It's not really that the image is reversed right and left. It's your perspective.

Think of your mirror this way, it is a piece of glass that your image is drawn upon.

Get a grease marker and write your name on the outside of a window. Then go inside and read what you wrote. It will read right to left even though (assuming English, western left to right writing here) you wrote it left to right.

What you view in the mirror is essentially your image from the other side of the glass. You are looking at yourself "from behind" so to speak. In same fashion as the grease pencil example above, your image will appear reversed left to right and right to left.
 
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