Question

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 the images for formed 10 cm away from the lens find the size of the image also

Answer 1

☆☆ranshsangwan☆☆

f = -20cm, v = -10cm, h = 4cm
1/v - 1/u = 1/f ........ 1/u = 1/v - 1/f ...... 1/u = -1/10 + 1/20 = -1/20
u = - 20cm = object distance
h'/h = v/u ......... h'/4 = -10/-20 ....... h'/4 = 1/2....
h' = 2cm = image height.