A luminous object is placed at a distance of 40 cm from a converging lens of focal length 25 cm. The image obtained in the screen is

In a convex lens, if the object is placed at 2F (twice of the focal length), the image formed will be -

A convex lens has a focal length of 15 cm. At what distance should an object be placed in front of the lens to get a real image of the same size of the object?

What is the magnification produced by a concave lens of focal length 10 cm, when an image is formed at a distance of 5 cm from the lens?

If an object is placed at the focus of a concave mirror, its image is

Where should an object be placed in front of a convex lens to get a real and enlarged image of the object ?