$A$ $14$ year old student is not able to see clearly the questions written on the blackboard placed at a distance of $5\, m$ from him.
$(a)$ Name the defect of vision he is suffering from.
$(b)$ With the help of labelled ray diagrams show how this defect can be corrected.
$(c)$ Name the type of lens used to correct this defect.

(N/A) The student is suffering from Myopia (near-sightedness).
$(b)$ The defect is corrected by using a concave lens of appropriate power. The concave lens diverges the incoming parallel rays from a distant object so that they appear to originate from the student's far point,allowing the eye lens to focus them on the retina.
$(c)$ $A$ concave lens is used to correct this defect.