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Optics class 12 Questions and Answers pdf 11. A convex lens and a concave lens, each having the same focal length of 25 cm, are put in contact to form a combination of lenses. The power of the combination (in dioptres) is (a) zero (b) 25 (c) 50 (d) infinity |
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Answer» Power of the combination = 0 D.Explanation:f1 = 25 CM (CONVEX lens)f2 = - 25 cm (Concave lens)Focal LENGTH of LENSES in combination :1/f = 1/25 - 1/25 = 0/25 = 0Power = 1 / focal lengthP = 1 /f = 0 D |
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