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A thin convex lens made from crown glass (mu = (3)/(2)) has focal length f. When it is measured in two different liquids having refractive indices (4)/(3) and (5)/(3), it has t he focal length f_(1) and f_(2) respectively. The correct relation between the focal lenghts is : |
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Answer» `f_(1) and f_(2)` both become negative `(1)/(f) = (mu - 1) ((1)/(R_(1))-(1)/(R_(2)))` `(1)/(f) = ((3)/(2)-1)((1)/(R_(1))-(1)/(R_(2)))` `THEREFORE (1)/(f)=(1)/(2)((1)/(X))rArrf=2x,((1)/(x)=(1)/(R_(1))-(1)/(R_(2)))` `(1)/(f_(1))=((3//2)/(4//3)-1)((1)/(x))rArr(1)/(f_(1))=(1)/(8X)=(1)/(4f)rArrf_(1)=4f` `rArr(1)/(f_(2))=((3//2)/(5//3)-1)((1)/(x))=rArrf_(2)=-ve` |
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