a convex lens produces a double sized real image when an object is placed at a distance of 18 cm from it.where should the object be placed to produce a triple size real image?
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in Ist case m=-2
u=-18
m=v/u
v=mv
= -2*-18=36
1/f=1/v-1/u
= 1/36+1/18
= 1/12 ..
in case (2) m=-3
let u=-x
v= -3*-x=3x
1/f=1/v-1/u
1/12=1/3x+1/x
1/12=4/3x
x=16
therefore object is plced at -x==-16 cm
u=-18
m=v/u
v=mv
= -2*-18=36
1/f=1/v-1/u
= 1/36+1/18
= 1/12 ..
in case (2) m=-3
let u=-x
v= -3*-x=3x
1/f=1/v-1/u
1/12=1/3x+1/x
1/12=4/3x
x=16
therefore object is plced at -x==-16 cm
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