In order to obtain a real image of magnification 2 using a converging lens of focal length 20 cm, where should an object be placed

50 cm

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30 cm

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– 50 cm

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– 30 cm

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Solution

The correct option is D – 30 cm
For real image m=-2

$∴$ M = $\frac{f}{u + f} \Rightarrow - 2 = \frac{f}{u + f} = \frac{20}{u + 20} \Rightarrow$ u=-30 cm.

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In order to obtain a real image of magnification 2 using a converging lens of focal length 20 cm, where should an object be placed

The correct option is D – 30 cmFor real image m=-2 ∴ M = fu+f⇒−2=fu+f=20u+20⇒ u=-30 cm.

The correct option is D – 30 cm
For real image m=-2

$∴$ M = $\frac{f}{u + f} \Rightarrow - 2 = \frac{f}{u + f} = \frac{20}{u + 20} \Rightarrow$ u=-30 cm.