InterviewSolution
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InterviewSolution
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An object is placed at a distant of `1.50` from a screen and a convex lens placed in between produces an image magnified `4`times on the screen .What is the focal length and the position of the lens. |
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Answer» The information given in the question ray diagram.It is given that `m=(1)/(O)=-4` Lets lens is placed at a distance of`x` from the object.Then u=-x,and v=(1.5-x) using`m=(v)/(u),"we get"-4=(1.5-x)/(-x)` or 4x=1.5-x or 5x=1.5 Thus x=0.3 metre The lens is placed at a distance of 0.3m from the object (or`1.20m`from the screen) For focal length,we may use `m=(f)/(f+u)` or`-4=(f)/(f+(-0.3))` or`-4f+1.2=f` or`5f=1.2` thus`f=(1.5)/(5)=0.24` The focal length is `0.24m(or 24cm)` |
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