A converging lens is used to produce an image of an object on a screen. What change is needed for the image to be formed nearer to the lens?

Which of the following can make a parallel beam of light when light from a bulb falls on it?

In order to obtain a real image twice the size of the object with a convex lens of focal length 15 cm, the object distance should be:

A convex lens of focal length 8 cm forms a real image of the same size as the object. The distance between object and its image will be:

A virtual, erect and magnified image of an object is to be obtained with a convex lens. For this purpose, the object should be placed: