Question

a lens of focal length 12cm forms an erect image, three times the size of the object. the distance between the object and the image is:
8cm
16cm
24cm
36cm​

Answer 1

Answer:

(b) 16 cm

Explanation:

Magnification, m = v/u

3 = v/u

⇒ v = 3u

Lens formula : 1/v – 1/u = 1/f

1/3u = 1/u = 1/12

-2/3u = 1/12

⇒ u = -8 cm

V = 3 × (-8) = -24

Distance between object and image = u – v = -8 – (-24) = -8 + 24 = 16 cm

Answer 2

Answer:

16 cm

Explanation:

16