Question

The focal length of a converging lens is 20cm. An object is 60cm from the lens. Where will be the image is formed. write the nature of the image

Answer 1

Focal length = distance between focus and centre of curvature =20cm
since ,2F=40cm
It is given that object is kept at 60 cm from centre of curvature
since object at beyond 2F


nature of object =Real and Inverted
size of object =smaller than the object
position of object= Between the F and 2F on the other side of lens

Answer 2

Answer:

Given:

Object Distance (u) = - 60cm

Focal Length (f₁) = 20cm

To find: Image Distance (v)

From the Lens formula,

1/f = 1/v - 1/u

We get, v = f x u/ f + u

= v = 20 x (-60)/ 20 - 60

= 20 x 60/40 = 30cm

⇒ Image Distance = 30cm

∴ The image is formed in between F₁ and 2F₁.

  Nature of the Image is (a) Real (b) Dimenished (c) Inverted

(ii) Given:

Height of the Object () = 2cm

To find: Height of the Image ()

We know that,

=  =  ⇒  = 30/-60 = 1/-2 ⇒  ⇒  = -1cm

∴ Height of the Image is 1cm, which is below the principal axis.

⇒ For more Clarification, you can observe the figure in the Attachment.