Question

The focal length of a concave lens is 20cm. If an object is kept at a distance of 30cm from the lens, find out the distance to the image formed.

Answer 1

u = -30cm , f = -20cm

1/f = 1/v - 1/u

1/-20 = 1/v - 1/-30

1/v = 1/-20 + 1/-30

f/v = 12

v = -12cm