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Question
An illuminated object is placed on the principal axis of a converging lens so that a real image is formed on the other side of the lens. If the object is shifted a little,
Options
the image will be shifted simultaneously with the object
the image will be shifted a little later than the object
the image will be shifted a little earlier than the object
the image will not shift
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Solution
the image will be shifted a little later than the object
Light rays emitting from a source have to cover some optical distance to form an image of the source on the other side of the lens. So, when a light source is shifted by some distance on the principal axis, then the light rays emitting from the new position of the source take some time to form a shifted image of the object on the other side of the lens. However, this delay is very small because the speed of light has a very larger value.
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