Question

An object placed at a distance of 9cm from first
principal focus of convex lens, produces a real
image at a distance of 25cm from its second
principal focus. Then focal length of lens is
(1) 9 cm
(2) 25 cm
(3) 15 cm
(4) 17 cm​

Answer 1

Answer:

25 cm first focous 25cm so second also 25