Draw a diagram to show how a converging lens held close to the eye acts as a magnifying glass. Why is it usual to choose a lens of short focal length for this purpose rather than one of long focal length?

A converging lens as a magnifying glass:

It is usual to choose a lens of short focal length for this purpose rather than one of long focal length because the smaller the focal length of a convex lens, the greater will be its magnifying power.

Explanation

A convex lens can produce an enlarged or magnified image (larger than the object) of an object when it is held within the focus, $F$ 

( between optical centre, $C$ and focus, $F'$ ) of a convex lens.

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Updated on: 10-Oct-2022

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