An object 4cm high is placed at a distance of 10cm from a convex lens of focal length 20cm. Find the position, nature and size of the image.
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$u =-10 cm h _1=4 cm$ f = 20cm$\frac{1}{\text{v}}-\frac{1}{\text{u}}=\frac{1}{\text{f}}$
$\frac{1}{\text{v}}-\frac{1}{-10}=\frac{1}{20}$
$\frac{1}{\text{v}}=\frac{1}{20}-\frac{1}{10}=-\frac{1}{20}$
$\text{v}=-20\text{cm}$ (Image is 20cm in front of the convex lens)
$\text{m}=\frac{\text{v}}{\text{u}}=\frac{20}{-10}=-2$
$\text{m}=\frac{\text{h}_2}{\text{h}_1}=-2$
$\frac{\text{h}_2}{4}=-2$
$\text{h}_2=-8\text{cm}$
Image is 8cm in size and is real and inverted.
$\frac{1}{\text{v}}-\frac{1}{-10}=\frac{1}{20}$
$\frac{1}{\text{v}}=\frac{1}{20}-\frac{1}{10}=-\frac{1}{20}$
$\text{v}=-20\text{cm}$ (Image is 20cm in front of the convex lens)
$\text{m}=\frac{\text{v}}{\text{u}}=\frac{20}{-10}=-2$
$\text{m}=\frac{\text{h}_2}{\text{h}_1}=-2$
$\frac{\text{h}_2}{4}=-2$
$\text{h}_2=-8\text{cm}$
Image is 8cm in size and is real and inverted.
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