Question

An object is placed at a distance 10cm from a lens of power 4D. find position and nature of image

Answer 1

here

u = -10 cm

f = 100/P cm = -100/4 cm = -25 cm



the image distance can be calculated using the following relation

1/f = 1/v - 1/u

or

1/v = 1/f +1/u

or

1/v = -1/25 - 1/10

or

the image distance is

v = 7.14 cm

Answer 2

plz refer to this

hope it helps