$A$ person can see distant sign boards clearly but cannot read clearly a book which is at $25\, cm$ from his eye. Giving reason,identify the defect. Draw a labelled ray diagram to illustrate this defect and its correction.

(N/A) The person is suffering from Hypermetropia (farsightedness).
Reasons for this defect:
$(a)$ The eyeball has become too short,so that light rays from a nearby object are focused at a point behind the retina.
$(b)$ The focal length of the eye lens is too long because the ciliary muscles are unable to make the lens sufficiently convex.
This defect is corrected by using a convex lens of appropriate power,which converges the light rays before they enter the eye,allowing them to focus on the retina.