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A lens has power 4 D. Find the focal length that lens. |
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Answer» Given Focal length (f) = 4D P (in diopter) = \(\frac{1}{f(in\,meters)}\) ⇒ 4 = \(\frac{1}{f(in\,meters)}\) ⇒ f (in meters) = \(\frac14\)= 0.25m Now 1m = 100cm ⇒ 0.25m = 25cm Hence the focal length of lens is 25cm. |
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