Question

an object 2 cm height is placed 20cm in front of convex lens of focal length 10 cm find the distance from the lens at which screen should be placed in order to obtain sharp image what will be the size and nature of image?

Answer 1

image is real and inverted

Answer 2

Answer:

The object should be placed at 20cm.

It is real and inverted.

Explanation:

It is given that height of object is $2cm$

$u=20cm$

$f=-10cm$

Using lens formula

$\frac{1}{f} =\frac{1}{v}-\frac{1}{u}$

$\frac{1}{-10} =\frac{1}{v}-\frac{1}{20}$

$v=-20cm$

Hence, object should be placed at $20cm$.

Also, $-\frac{v}{u}=\frac{height of image}{height of object}$

Height of image$=-2cm$

Image is real and inverted.

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