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1. A lens has a refractive index 1.5 and itsfocal length is 20 cm while in air. The samelens is put in a liquid having 1.25 refrac-tive index. So find the focal length of thelens while in liquid. |
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Answer» 20.20 is the correct answer sorry it is wrong ok we can use the lens makers formula to solve this problem. Lens makers formula is For lens in air 1/20 = (1.5–1)(1/R1–1R2) (1/R1 - 1/R2) = 2/20 = 1/10 When lens immersed in water1/f'= (1.5/1.25 –1)(1/R1–1/R2) 1/f' = (6/5 - 1) * 1/10 1/f' = (1/5) * 1/10 f' = 50 cm |
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