A convex lens is cut in half along its principal axis and the two halves are separated by a distance of 12 cm. An object is placed 6 cm in front of the lens as shown in Figure. Two sharp images are formed on the screen placed 80 cm from the object. What is the focal length of the lens ?
A convex lens forms a real image of a point object placed on its principal axis. If the upper half of the lens is painted black,