Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer
(a) The eye defect shown is Myopia (Near-sightedness). In this defect, the image is formed in front of the retina instead of on it.
(b) Two causes of myopia:
- Excessive curvature (elongation) of the eye lens.
- Elongation of the eyeball.
(c) Myopia is corrected using a concave lens of suitable focal length.
Diagram:
```
Incoming [Concave] EYE
light rays → lens → ___
\ → ( | → / \
\ → | →| image|
/ → | → \___/ ← on retina
```
A concave lens diverges the light rays so that they converge exactly on the retina.
---
Explanation
- The diagram in the question shows image forming in front of the retina → myopia. (If it were behind, it would be hypermetropia — read the diagram carefully in the exam.)
- For causes, always give two distinct biological/structural reasons — elongated eyeball and increased lens curvature are the standard NCERT answers.
- The correction diagram must show: parallel rays → concave lens → rays diverge → converge on retina. Draw and label clearly; examiners award 1 mark for the diagram alone.
- Part (a) is ~1 mark, (b) ~1 mark (½ each), (c) ~1 mark (diagram). Adjust if your paper allocates differently.