The power of a lens is +2 D. Its focal length is MCQ with Answer and Explanation

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The power of a lens is +2 D. Its focal length is

A. 50 cm

B. 2 m

C. 20 cm

D. 0.5 m

Answer: Option D

Solution (By JKSSB Mock Tests)

Power P = 1/f (in metre). f = 1/P = 1/2 = 0.5 m = 50 cm. Positive power indicates convex lens. For concave lens, power negative. Dioptre (D) is SI unit of power. Remember f in metres.

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