Instructions for:Plus/Minus Mirrors
Two mirrors are mounted on a piece of hard board. They are identical, spherically-curved mirrors, oriented in opposite directions, so that one is seen as a converging mirror, the other a diverging mirror.
These mirrors allow exploration of the properties of curved mirrors. The diverging mirror (that bulges out in the middle) makes reflected images appear smaller then they would in a flat mirror. Here is a ray diagram that explains how this comes about:
Click to enlarge the diagram
What you see in the converging mirror (like the inside of a bowl) depends on how far away it is from the viewer. From a distance it produces an inverted image (upside down). This diagram shows how light rays from such a mirror are reflected, and reconvene to appear as if they come from a point in front of the mirror, producing a visible image.
Click to enlarge diagram
Viewed from a short distance the mirror will give a magnified view of your eye.
Note:Denting or deforming the mirrors isn't good for them.
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Copyright 2004 Straley/Pinney - The University of Kentucky Physics Petting Zoo