(a) A lens forms a blurred image of an object on the screen as shown below:
What changes can you make to the following to form a sharp and in-focus image on the screen?
(i) object distance
(ii) focal length of the lens
From the diagram we can tell that the object is not at infinity, neither at the focus.
It can either be at C, between C and F, or between F and O.
This can be achieved in two ways:
(i) decrease the object distance
(ii) increase the focal length