Question

A converging lens has a focal length of 15 cm. At what distance should an object from the optical centre of the lens be placed so that its real image is formed at 30 cm on the other side of the lens?

Answer 1

Answer:

Here f = +15 cm

v = - 30cm

u=?

Using lens formula,

1/f = 1/v-1/u

1/15= 1/-30 - 1/u

1/15 + 1/30 = - 1/u

1/10 = - 1/u

Therefore u= - 10 cm

Hence object should be placed at a distance of 10 cm from optical centre.

Hope it helps you ✌️

Answer 2

Answer:

the object should be kept at 2F1 i.e. 30 cm away from the optical centre