Question

11. A concave lens of focal length 15 cm forms an image, 10 gm from the lens. How fa
is the object placed from the lens? Draw the ray diagram.
12. An object is placed at a distance of 10 cm from a convex mirror of focal len​

Answer 1

Answer:

11:Focal length (f ) = -15 cm

Distance of image (v) = -10 cm

1v–1u=1f

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.