At what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 24 cm from it on the other side. What will be the magnification produced in this case?
CBSE DELHI - SET 1 2010
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$\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$$\frac{1}{u} = \frac{1}{24} - \frac{1}{18}$
$= \frac{3 - 4}{72} = \frac{-1}{72}$
$\therefore u = -72 \text{ cm}$
Object should be placed at a distance of 72 cm from the lens.
$m = \frac{v}{u}$
$= \frac{+ 24}{-72}$
$= \frac{3 - 4}{72} = \frac{-1}{72}$
$\therefore u = -72 \text{ cm}$
Object should be placed at a distance of 72 cm from the lens.
$m = \frac{v}{u}$
$= \frac{+ 24}{-72}$
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