Question

an concave lens of focal length 15 cm forms an image 10 cm from the lens how far is the object from the lens . Draw the ray diagram ​

Answer 1

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