Question

Where is an image of an object is formed and what is its nature in case of convex lens when:

1. Object is at infinity with respect to focal length of lens?
2. Object is beyond 2F of the lens?
3. Object is at 2F of the lens?
4. Object is in between the F and 2F of the lens?
5. Object is at principal focus of lens?
6. Object is in between the principal focus and optical centre of lens?

Answer 1

For a convex lens:

1. The image forms at the principal focus on the other side of the lens. It is real, inverted and extremely diminished (almost a point).
2. The image forms between F and 2F on the other side of the lens. It is real, inverted and diminished.
3. The image forms at 2F on the other side of the lens. It is real, inverted and the same size as the object.
4. The image forms beyond 2F on the other side of the lens. It is real, inverted and enlarged.
5. The image forms at infinity. It is real, inverted and highly enlarged.
6. The image forms on the same side of the lens as the object. It is virtual, erect and enlarged.