Answer:
Focal length (f ) = -15 cm
Distance of image (v) = -10 cm
\(\begin{array}{l}\frac{1}{v} – \frac{1}{u} = \frac{1}{f}\end{array} \)
1/u = -(1/10) – (1/- 15)
1/u =1/15 – 1/10
1/u = -0.033
u = -30 cm
So, the object is placed 30 cm away from the concave lens.
Ray diagram:
