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))#