Q1. [3] § Chapter Introduction § 10.2 DEFECTS OF VISION AND THEIR CORRECTION
Study the diagram given below and answer the questions that follow :
(i) Name the defect of vision depicted in this diagram stating the part of the eye responsible for this condition.
(ii) List two causes of this defect.
(iii) Name the type of lens used to correct this defect and state its role in this case.
Previously asked in CBSE board exam
2024 31/5/1 Q31 (a)
Generated by claude-sonnet-4-6 · 2026-06-15 06:52 · grounding rag
Model Answer
(i) The defect shown is Hypermetropia (Far-sightedness). The part responsible is the eye lens — either its focal length is too long, or the eyeball is too small, causing the image to form behind the retina.
(ii) Two causes:
- The focal length of the eye lens is too long.
- The eyeball has become too small.
(iii) A convex (converging) lens is used to correct this defect. It provides the additional converging power needed to bring the image forward onto the retina, enabling clear near vision.
Source: Chapter 10, Section 10.2 (b) Hypermetropia
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Explanation
- The diagram shows rays focusing behind the retina → this is the key identifier for Hypermetropia (not Myopia, where rays focus in front).
- Examiners expect you to name the responsible part (eye lens/eyeball shape) and both causes explicitly.
- For the lens correction, say convex/converging and state its role (brings image onto retina) — both are needed for full marks.
- Do not confuse: Myopia → concave lens; Hypermetropia → convex lens.
If a question refers to an image, map, graph or diagram that is not shown here, find the actual CBSE question paper on the CBSE website:
cbse.gov.in.