Virtual image
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Top: The formation of a virtual image using a concave lens. Bottom: The formation of a virtual image using a convex mirror. In both diagrams, f is the focal point, O is the object and I is the image, shown in grey. Solid blue lines indicate light rays. It can be seen that the light rays appear to emanate from the virtual image but do not actually exist at the position of the virtual image. Thus an image cannot be formed by placing a screen at the position of the virtual image. |
In
optics, a
virtual image is a representation of an actual object (source) formed by diverging
rays of
light which seem to originate from the
image, but in reality do not come from that position. A screen or an observer placed where a virtual image appears to be cannot actually "see" it.
For example, a
plane or
convex mirror forms a virtual image positioned behind the mirror. Although rays of light seem to come from behind the mirror, light from the source spreads and exists only in front of the mirror.
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Real image*
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