Q5 of 58 Page 1

What is meant by power of a lens? Define its SI unit.

Power is defined as the reciprocal of its focal length and is a measure of the degree of convergence or divergence of light rays falling on the lens. The S.I. unit of power of a lens is Diptre.

1 dioptre is the power of the lens whose focal length is 1m.


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(b) whether it is a metal or non-metal,


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