Science — CBSE Class 10 board question

Causes of Myopia:
Myopia arises due to:

1. Excessive curvature of the eye lens, or
2. Elongation of the eyeball.

(a) Image formation by a myopic eye:

In a myopic eye, the image of a distant object is formed in front of the retina instead of on it.

```
Distant object → Eye lens → Image (formed in front of retina) ✗ Retina
```
(Ray diagram: parallel rays from distant object converge before the retina)

(b) Correction of myopia:

A concave lens of suitable power is used. It diverges the incoming rays so that they converge exactly on the retina.

```
Distant object → Concave lens → Eye lens → Image (on retina) ✓
```
(Ray diagram: concave lens diverges rays; eye lens then focuses them onto the retina)

Source: The Human Eye and the Colourful World, Section 10.2

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• The question is 3 marks: ~1 mark for causes, ~1 mark for each diagram (described/drawn). Keep causes brief (2 points) and diagrams clearly labelled.
• Since this is a written exam, draw actual ray diagrams on paper with labels: "Retina," "Eye lens," "Image," and for correction — "Concave lens." The examiner specifically looks for the image forming in front of the retina (myopia) and on the retina (after correction).
• Never confuse myopia correction (concave lens) with hypermetropia correction (convex lens).