Question

A concave lens has focal length 30cm. At what distance should the object be placed from the lens
so that it forms and image at 20cm from the lens. Also find magnification produced by the
lens.​

Answer 1

Answer:

u = 60

m = 1/3

Explanation:

lens formula = 1/f = 1/u + 1/v

1/u = I/f - 1/v

1/u = 1/30 - 1/20

1/u = 20-30/600

1/u = 10/600

u = 60

m = v/u

= 20/60 = 1/3

Hope it helps u