The correct answer is A = at F
When an object is placed at infinity, the real image is formed at the focus. The size of the image is much smaller than that of the object. Convex Lens. ... Rays of light that pass through the lens are brought closer together (they converge). A convex lens is a converging lens. When parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.
Because a convex lens concentrates the light rays that are incident on it, it is called a converging lens. The bending of rays is maximal at the top and bottom of the lens. This is because the top and bottom prisms have the greatest angle between the refracting surfaces.When an object is at infinity,then the rays coming from it is almost parallel to principal axis. Hence the image formed is at focus.A converging lens produced a virtual image when the object is placed in front of the focal point. For such a position, the image is magnified and upright, thus allowing for easier viewing.
A concave lens is thinner in the middle and thicker at the edges. A convex lens is thicker in the middle and thinner at the edges. Used in the camera, focus sunlight, overhead projector, projector microscope, simple telescope, magnifying glasses, etc.Real images can be magnified in size, reduced in size or the same size as the object. Real images can be formed by concave, convex and plane mirrors. Real images are not virtual; thus you could never see them when sighting in a mirror. Real images result when the reflected light rays diverge.
Convex lens is also called converging lens. However, it should be noted that convex can also show diverging behaviour when object is very close to the lens. If refracted rays appear to diverge from a single point, then this is called as diverging behaviour of the lens. This is observed when a virtual image is formed.