Question

what is Magnification
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Answer 1

the action of magnifying something or the process of being magnified.

Answer 2

If it is from chapter light then the answer is this:

Magnification is the ratio of size of image formed by the mirror or lens to the size of object. If magnification value ( only value not sign of magnification) is less than 1 then the image is smaller than than object size, if it is greater than 1 it is greater than the object, if it is equal to 1 than it has size equal to the object.