• Cralder@lemmy.world
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    1 month ago

    This is actually really interesting and I think about it every time I look in a large mirror. IIRC it is because the mirror is always “halfway” between you and your mirror image. So as you step back your mirror image gets further away and looks smaller, but so does the mirror.

    • unexposedhazard@discuss.tchncs.de
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      1 month ago

      Nah if u step back far enough it should show your whole body. The only exception being if its angled weirdly or if its not flat but curved in a special way.

      • Bassman1805@lemmy.world
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        1 month ago

        Nope, the geometry actually works out such that it doesn’t matter your distance from the mirror, only how tall the mirror is and how high it’s mounted.

        A mirror that is as half as tall as your, mounted at head height, will show your white whole body regardless of how far away you are from it. TECHNICALLY, the bottom edge must be halfway between your eyes and feet, and the top edge must be halfway between your eyes and top of head.

      • bleistift2@sopuli.xyz
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        1 month ago

        If you’d be so kind, how far do you have to get away from a flat mirror to show your whole image?

        • unexposedhazard@discuss.tchncs.de
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          1 month ago

          Depends on the size of the mirror and how far it is off the ground. If its a full sized 2m tall mirror then the min distance is obviously zero. If its a small bathroom sink mirror that doesnt go down to the floor, then you need to be really far away, further than you can be in a bathroom.

          • Tar_Alcaran@sh.itjust.works
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            1 month ago

            Uhhh no, that’s not how angles work.

            The further you get away from a mirror, the “further away” the reflection is. You will never see your whole body in a hand mirror, even if you put it on the moon.

            • candybrie@lemmy.world
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              1 month ago

              The reflection being further is the point? The further away something is, the smaller it looks, so the less of your field of view it takes up, the more you can see of it.

              If I put my hand on my eye, I can’t see much of it. If I pull my hand back, I can see more of it. If I put a mirror on my eye, I can only see my eye. If I put it back, I can see my face because the reflection of my face is further (i.e. smaller).

              I’m very confused what you’re trying to say.

              • Tar_Alcaran@sh.itjust.works
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                1 month ago

                Ok, visualize it like this:

                Draw yourself, with a small mirror at head height, a meter away. Draw your reflection at the same distance from the mirror on the other side.

                Now do that again, but place the mirror 10 times further. Then draw lines from your eye, to the edge of the mirror, and to the reflection.

                You’ll reach the same point on your reflection.

                Edit: or let the BBC do it for you; https://www.bbc.co.uk/bang/images/dallas_mirror_diagram_large.gif