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Q56 (CISF/2022) Science & Technology › Basic Science (Physics, Chemistry, Biology)

Dioptre is the SI unit of :

Explanation

A dioptre (symbol: D) is the SI unit of the power of a lens or a curved mirror. The power of a lens (P) is defined as the reciprocal of its focal length (f) expressed in meters, represented by the formula P = 1/f. Therefore, 1 dioptre is equivalent to 1 m-1.

  • Size: Measured in standard units of length like millimeters or centimeters.
  • Curvature: While related to power, curvature is generally expressed as the reciprocal of the radius of curvature.
  • Magnification: It is a ratio of the height of the image to the height of the object (or distances), making it a dimensionless quantity with no units.

By convention, the power of a converging (convex) lens is positive, while the power of a diverging (concave) lens is negative.

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SIMILAR QUESTIONS

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An optician prescribes a power = -0.5 dioptre. The corresponding lens must be a

NDA-II · 2020 · Q92 Relevance score: 4.43

A lens has a power of + 2.0 Dioptre, Which one of the following statements about the lens is true?

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A myopic person has a power of - 1.25 Dioptre. What is the focal length and nature of his lens ?

NDA-II · 2018 · Q60 Relevance score: 3.87

If the focal length of a convex lens is 50cm, which one of the following is its power?