Q1. [2] § Chapter Introduction § 10.2 DEFECTS OF VISION AND THEIR CORRECTION
(A) Observe the following diagram and answer the questions following it :
(i) Identify the defect of vision shown.
(ii) List its two causes.
(iii) Name the type of lens used for the correction of this defect.
Previously asked in CBSE board exam
2023 31/4/1 Q25 (A)
Generated by claude-sonnet-4-6 · 2026-06-15 06:52 · grounding rag
Model Answer
(i) The defect shown is Myopia (near-sightedness). The image is formed in front of the retina instead of on it.
(ii) Two causes:
- Excessive curvature of the eye lens.
- Elongation of the eyeball.
(iii) A concave lens (diverging lens) of suitable power is used to correct myopia.
Source: Chapter 10, Section 10.2(a) – Myopia
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Explanation
- The diagram shows rays converging in front of the retina → this is the key identifier for myopia (not hypermetropia, where image forms behind the retina).
- Examiners specifically look for both causes stated clearly; missing one costs a mark.
- "Concave lens" must be named — writing only "diverging lens" may lose the mark if the term is not recognised as equivalent.
- This 2-mark question typically awards: 1 mark for defect + causes combined, 1 mark for corrective lens — so be concise and precise.
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.