Question

an object of hight 5cm is placed near infront of a convex lens of focal length 20cm .and image of hight 20cm is formed behind the lens find ? 1)u​

Answer 1

An object of height 5cm is held 20cm away from converging lens of focal length 10cm,Find the position, nature and size of the image formed

v=20cm, nature = real image, h

2

=5cm

Given, u=-20cm

f=10cm

v=?

We know

f

1

=

v

1

−

u

1

10

1

=

v

1

−

20

(−1)

v

1

=

20

2−1

v=20cm

We know

magnification (M)=

h

o

h

i

=

u

−v

or,

−20

20

=−1=

h

o

h

i

since,h

0

=5cm

so,h

i

=−5cm

nature = real image

Answer 2

Answer:

Image distance is 8.57 cm behind the convex mirror. As the v is positive the image formed is virtual and erect. This indicates that the image is diminished because the magnification of the image is less than 1