Question

The image of a need placed 45cm from a lens is formed on a screen placed 90cm on the other slide of the lens. find the displacement of the image when the object is moved 15cm away from lens.
please answer bta Dena bhai and sister log.​

Answer 1

Explanation:

Here, u = -45 cm, v = 90 cm

∴

f

1

=

v

1

−

u

1

=

90

1

+

45

1

=

30

1

⇒f=30cm

when the needle is move 5 cm away from the lens,

u=-(45 + 5) = -50 cm

∴

v

′

1

=

f

1

+

u

′

1

=

30

1

+

(−50)

1

=

150

2

=⇒v

′

=75cm

∴ Displacement of image = v-v' =90-75= 15 cm, towards the lens