(a) A student has difficulty in reading his textbooks but can read the blackboard clearly while sitting in the last row. Name the defect of vision the student is suffering from. List two reasons due to which this defect arises. Write the nature of the lenses required to correct this defect.

OR

(b) Draw a ray diagram to show the path of a ray of light falling obliquely on one of the refracting faces of a triangular glass prism and mark the angle of deviation on it.

Part (a): The chapter's in-text Q4 directly parallels this scenario: "A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from?" Being able to see the blackboard (distant) clearly but not the textbook (near) clearly is the defining symptom of myopia, described in Section 10.2(a): "A person with myopia can see nearby objects clearly but cannot see distant objects distinctly... This defect may arise due to (i) excessive curvature of the eye lens, or (ii) elongation of the eyeball... This defect can be corrected by using a concave lens of suitable power." A concave lens diverges the rays slightly before they enter the eye, effectively moving the point of convergence from in front of the retina back onto the retina.

Part (b) (alternative choice): This is a direct reproduction of Activity 10.1 in Section 10.3 of the chapter, where PE is the incident ray hitting face AB at E, EF is the refracted ray inside the glass prism, and FS is the emergent ray leaving face AC. The chapter states: "The peculiar shape of the prism makes the emergent ray bend at an angle to the direction of the incident ray. This angle is called the angle of deviation." The diagram must show the normal at E, the normal at F, angle of incidence ∠i at E, angle of refraction ∠r at E, and angle of emergence ∠e at F, with ∠D marked between the directions of the incident and emergent rays.