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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