Question

When object is placed 15cm in front of a convex mirror of focal length 10cm . find nature , position and size of image if height of object is 5cm.​

Answer 1

Answer:

Given: For convex lens u=−15cm f=10cm

To find: v

Solution: From lens formula

1v−

u

1

=

f

1

v

1

+

15

1

=

10

1

v

1

=

30

1

v=30cm

And magnification is =

−15

30

=−2

So for image is inverted and magnified and when a mirror is placed at a distance d behind lens then u for mirror is u

1

=−30+α

=α−30

and v=−30−14+α

From mirror formula

v

1

+

u

1

=

f

1

α−45

1

+

α−30

1

=

10

−1

(α−45)(α−30)

α−30+α−45

=

10

−1

(α−45)(α−30)

2α−75

=

10

−1

20α−750=−α

2

+75α−1350

α

2

=

−

+

(55)

2

−4/100

2

α=

2

55+−25

=40cm or 15cm

Hence d=15cm(as 40 cm not possible)

Answer 2

Answer:

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