A thin concave lens of focal length f is used to form images of real objects placed at different positions on its principal axis.
a. (i) Draw neat, well-labelled ray diagrams for the following four cases:
(1) the object at infinity,
(2) the object beyond 2F,
(3) the object at F,
(4) the object between F and the optical centre O. In each diagram mark the position and relative size of the image.
b. (ii) From the diagrams drawn in part (i), explain with proper reasoning why a concave lens always produces a virtual, erect and diminished image, irrespective of where the object is placed on the principal axis.