Question

a concave lens has the focal length of 20cms. at what distance should the object from the lens be placed so that it forms an image at 10cm from the lens? also find the magnification produced by the lens​

Answer 1

Answer:

Given f = - 20 cm, (sign convention) , v = - 10 cm

(∴ image formed by concave lens is virtual)

By using lens formula,

or u = - 20

Thus the object is placed at 20 cm from the concave lens