How Everything Works
How Everything Works How Everything Works

Question 419

Why do virtual images often look far away?
A virtual image is always located behind the optic (lens or mirror) that creates it. Thus when you look into a magnifying glass, eyepiece, or a make-up mirror, you see light that appears to come from beyond the optic that creates the image. You can't touch the virtual image or put your hand in the pattern of light that you seem to see. The virtual image can appear to come from just behind the optic or from a great distance behind that optic. It depends on how things are arranged. As you lift a magnifying glass off the surface of a newspaper, the virtual image of the newspaper starts just behind the glass and slowly moves back away from the glass. As the distance between the magnifying glass and newspaper approach the magnifying glass's focal length, the virtual image moves away to an infinite distance behind the glass. After that, there is no longer a virtual image at all. Instead, a real image begins to appear on the other side of the magnifying glass.

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