Full Length Mirrors

I saw this demo at last summer's (2009) meeting of the American Association of Physics Teachers. It was part of a really great presentation by Dr. Peter Hopkinson. The basic question was, "How large does a mirror need to be to see your whole body?" The concensus response from the audience of physics teachers was, "It depends on how far away you are from the mirror." As it turns out, the wisdom of crowds failed this one.

I managed to score a "full length" mirror from Target for $5. The mirror is one of those cheap ones you put on the back of a door and is nowhere near my height, it's about 2/3 my height. Yet if I mount it appropriately I can see my whole body at any distance. Just watch the video below for full details. Oh, and if you ever get a chance to see Dr. Hopkinson speak at a meeting you should jump at it!