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An object is placed at a certain distance from a convex lens of focal length 20 cm. Find the distance of the object if the image obtained is. magnified 4 times. |
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Answer» Solution :f = - 20 cm V =- 4 u ACCORDING to lens formula `(1)/(f) = (1)/(v) + (1)/(u)` `(1)/((-20))=(1)/((-4u))+(1)/(u)` `(1)/((-20))=(1)/(u)[-(1)/(4)+1]` `=(1)/(u)[(3)/(4)]` `u=(3xx20)/(4)=-15cm` |
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