Question

it was a divergent lens has a focal length of 20cm at what distance should an object of height 4 cm from the optical centre of the lens be placed so that image is formed 10 centimetre away from the lens find the find the size of the image also

Answer 1

Hi there!

Focal length, f = -20cm

Image distance, v = -10cm

Height, h = 4cm

⏩ By lens formula,

1/v - 1/u = 1/f

1/u = 1/v - 1/f

1/u = -1/10 + 1/20 = -1/20

u = - 20cm (Object distance)

⏩Height of Image:

h'/h = v/u

h'/4 = -10/-20

h'/4 = 1/2....

h' = 2cm (Image height)

Cheers!