Q1. [2] § 10.2 DEFECTS OF VISION AND THEIR CORRECTION
Observe the following diagram showing an image formation in an eye :
(a) Identify the defect of vision shown in the figure.
(b) List its two causes and suggest a suitable corrective lens to overcome this defect.
Previously asked in CBSE board exam
2023 31/5/1 Q25
Generated by claude-sonnet-4-6 · 2026-06-15 06:52 · grounding rag
Model Answer
(a) The defect shown is Myopia (near-sightedness). The image of a distant object is formed in front of the retina instead of on it.
(b) Two causes:
- Excessive curvature of the eye lens.
- Elongation of the eyeball.
Corrective lens: A concave lens of suitable power is used to correct myopia, as it diverges light rays to bring the image back onto the retina.
Source: Chapter 10, Section 10.2 – Defects of Vision and their Correction
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Explanation
- The diagram clearly shows image forming in front of the retina → always Myopia.
- Examiners expect both causes listed separately for full marks.
- Name the corrective lens specifically as concave lens (diverging lens); just writing "lens" won't fetch marks.
- This is a 2-mark question but has three parts (identify + two causes + lens), so keep each point crisp — one line each.
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.