Question

An object of size 7cm is placed at 27cm infornt of a convex mirror of focal length 18cm. At whose distance from the mirror should the screen be placed so that a sharp focussed image can be obtained. find the size and nature of the image

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Answer 1

Explanation:

An object of size 7 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained ? Find the size and the nature of the image.

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ANSWER

Mirror formula :

v

1

+

u

1

=

f

1

...........(1)

So, u=−27cm

Concave mirror have negative focal length.

f=−18cm

Putting the values in (1),

v

1

+

−27

1

=

−18

1

We get , v=−54cm

Also,

Magnification =

h

1

h

2

=

u

−v

7.0

h

2

=−

−27

−54

h

2

=−14.0cm

Image will be real and inverted and will be of size 14 cm.