Question #cf067

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Answer 1 · 2016-12-12T06:02:52

We know the lens formula as follows

$1/v+1/u=1/f$

where

$u->"object distance"=-ve$

$v->"imsge distance"=+ve$

$m->"magnification"=-1$

$color(red)"since real image is formed"$

$"Now " v/u=m=1=>v=-u=$

$f->"focal length"=f" for convex lens"$

So the above equation becomes

$-1/u-1/u=1/f$

$=>u=-2f$

Hence it is possible when

$color(blue)("object distance"(u) = 2xx"focal length"(f))$