Question

The length of an object is 4 cm. An image of length 6 cm is obtained when it is placed at

a distance of 2 cm in front of a convex lens. What is the linear magnification and image

distance?​

Answer 1

GIVEN -

height of object = ho = 4 cm

height of image = hi = 6 cm

Object distance = u = ( - 2 cm )

[ object distance is always taken as negative in case of convex lens ]

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$magnification = \frac{hi}{ho} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{6}{4} = \frac{3}{2} = (+ 1.5) \\ \\ \\ \\ thus \: image \: distance \: = \frac{hi}{ho} = \frac{v}{u} \\ = > \frac{3}{2} = \frac{v}{2} \\ = > v = \frac{3}{2} \times 2 \\ = > v = 3cm$