Fill in the blanks .

1.  If the object is kept at the focal point of a convex lens, the image is formed at ___________ .

2. Real image is obtained only in  ___________  lens.

3. For aconcave lens , the image formed is always ______________ irrespective of the position of object .

or a convex lens the focal point is the transition point between getting a real image and a virtual image. If the object is at a greater distance then F you get a real image. If the object is closer to the lens then F you get a virtual image. If the object is located at F the light rays from the object leave the lens parallel and never form any kind of image.