What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.
(a) -60 cm, Diverging
(b) 10 cm, Converging
(c) -10 cm, Diverging
(d) 60 cm, Converging
