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Name: Danielle
Status: other
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Question:
Why do some mirrors make you look skinny and others make you look fat? Is this due to slight concave or convex curvatures of what should be flat surfaces? i.e., dressing room mirrors that make you look thin or the "fat" mirror in the house that makes everyone have an extra bulge around the middle?



Replies:
Danielle, A completely flat mirror will show an image behind it of exactly the same shape and size as the actual object. Slight curvature along only one axis can make a person look fat or skinny. To make you look thin, your image needs to be compressed horizontally or extended vertically. Most mirrors bend over time top to bottom. If seen from the side, there is a slight curvature in the edge. The top and bottom edges are usually straight. Your home mirror can do this due to its own weight. If the center bulges out a little bit, your height will appear slightly smaller but your width will not be changed. This can make a person look a little fat. If the center bends back a little, then you can look a little taller without looking any wider. Mirrors can bend along other axes, but the one described is most likely.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College



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