Question

An object is placed at 30cm distance from the optical centre of a convex lens. Image formed at 30cm distance from the pole. Find the focal length of the lens​

Answer 1

Explanation:

u = -30cm

v = 30cm

1/f = 1/v - 1/u

1/f = 1/30 - (-1/30)

1/f = 1/30 + 1/30

1/f = 2/30

1/f = 15

f = 15cm

therefore, the focal length of the lens is 15cm