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प्रश्न
Differentiate the eye defects: Myopia and Hypermetropia
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उत्तर
| Myopia | Hypermetropia |
| Myopia, also known as short-sightedness, occurs due to the lengthening of the eyeball. | Hypermetropia, also known as long-sightedness, occurs due to the shortening of the eyeball. |
| With this defect, nearby objects can be seen clearly but distant objects cannot be seen clearly. | With this defect, distant objects can be seen clearly but nearby objects cannot be seen clearly. |
| The focal length of the eye lens is reduced or the distance between the eye lens and retina increases. | The focal length of the eye lens is increased or the distance between the eye lens and retina decreases. |
| The far point will not be infinity for such eyes and the far point has come closer. | Hence, the near point will not be at 25 cm for such eyes and the near point has moved farther. |
| Due to this, the image of distant objects is formed before the retina. | Due to this, the image of nearby objects is formed behind the retina. |
| This defect can be corrected using a concave lens | This defect can be corrected using a convex lens. |
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संबंधित प्रश्न
What is myopia?
What is the other name for
hypermetropia
Name the body part with which the terms myopia and hypermetropia are connected.
A person having short-sight cannot see objects clearly beyond a distance of 1.5 m. What would be the nature and power of the corrective lens to restore proper vision?
The defect of vision which cannot be corrected by using spectacles is:
(a) myopia
(b) presbyopia
(c) cataract
(d) hypermetropia
A person cannot see the distant objects clearly (though he can see the nearby objects clearly). He is suffering from the defect of vision called:
(a) cataract
(b) hypermetropia
(c) myopia
(d) presbyopia
Though a woman can see the distant object clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called:
(a) long-sight
(b) short-sight
(c) hind-sight
(d) mid-sight
A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:
- if the person is an old man
- if the person is a young man
Choose the Odd One Out:
A person is unable to see clearly a poster fixed on a distant wall. He however sees it clearly when standing at a distance of about 2 m from the wall.
- Draw ray diagram to show the formation of image by his eye lens when he is far away from the wall.
- List two possible reasons of this defect of vision.
- Draw ray diagram to show the correction of this defect using appropriate lens.
