The lower half of a convex lens is painted black. If an object is placed in front of the lens, then

If the top half of a convex lens is covered with black paper

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

Describe with the help of a ray-diagram, the size, nature and position of the image formed by a convex lens when an object is placed beyond 2f in front of the lens.

A convex lens forms a virtual image of an object placed ………… .

Find the focal length of a convex lens which produces a real image at 60 cm from the lens when an object is placed at 40 cm in front of the lens .

An optical system consists of a thin convex lens of focal length 30 cm and a plane mirror placed 15 cm behind the lens. An object is placed 15 cm in front of the lens. The distance of the final image from the object is