Question

a concave lens of focal length is 15 cm
an image lo cm from the lens. How for
is the object placed from the lens ?​

Answer 1

1/f=1/v+1/u

1/- 15=1/- 10 + 1/u

1/- u= 1/15 - 1/10

1/- u = 2- 3/30

1/- u= - 1/30

1/u = 1/30

u= 30

therefore object distance is 30 cm

Answer 2

Answer:

-30 cm

Explanation:

1/v-1/u=1/f

U=?

F=-15 cm

V=-10 cm

=

-1/10-(-1/15) =1/u

or, -30 cm