Question

find the position of an object of hieght 5cm in front of concave lens of focal length 20cm to get the image at a distance of 15cm of the lens also find height

Answer 1

Answer:

Explanation:

Given –

Convex lens.

Height of the object = 5 cm.

Object Distance = -10 cm.

Focal length = 15 cm.

To Find –

Height of the Image.

Nature of the Image.

Position of the Image.

Solution –

Refer the attachment for the diagram.

Lens Formula : 1/v - 1/u = 1/f.

➸ 1/v - 1/-10 = 1/15

➸ 1/v + 1/10 = 1/15

➸ 1/v = 1/15 - 1/10

➸ 1/v = (10 - 15)/150

➸ 1/v = -5/150

➸ 1/v = -1/30

➸ v = -30 cm

Hence, the position of the image is 30 cm in front of the lens.

The nature of the image formed is virtual and erect.

The size of the image is enlarged.

Now, We know Magnification = v/u = h'/h.

Hence, -30/-10 = h'/5

➸ 3 = h'/5

➸ h' = 15 cm

Hence, height of the image formed is 15 cm.