Question

what is meant by power of lens what is its SI unit name the type of lens whose power is positive the image of an object formed by a lens by a lens is real inverted and the same size as the object if the image is at a distance of 40 cm from the lens what is the nature and power of the lens draw ray diagram to justify your answer​

Answer 1

Power of a lens

is defined as the ability of a lens to converge/ diverge the light rays falling on it. It is the reciprocal of focal length of the lens in metre. P=1/f. Its unit is dioptre.

Explanation:

The S.I unit of power is dioptre (symbol D) power of lens = 1/ focal length ( in meter) when focal length is 40 that mean it is positive so therefore the resulting power will also be positive.

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