Human Eye And Defects Of Vision
A patient can see distant objects clearly but struggles to focus on nearby print, and an optometrist wants the correct classification and remedy.
Select the correct option:
Solution
Hypermetropia, corrected with a converging convex lens
NCERT explains that hypermetropia, or far-sightedness, occurs when the eye's near point recedes beyond the normal 25 cm, so nearby objects form their image behind the retina because the eye's converging power is insufficient. Since distant vision remains clear, the defect specifically affects close work, exactly as described. The remedy is a converging convex lens, which adds the missing converging power so that near objects focus precisely on the retina. The option naming myopia with a concave lens is wrong because myopia is the opposite defect, where distant objects blur, not near ones. The option pairing hypermetropia with a concave lens is wrong because a diverging lens would worsen the shortfall in converging power. The option pairing myopia with a convex lens misidentifies both the defect and its correction. As stated in NCERT Class 12, Chapter 9, hypermetropia is corrected using convex lenses of suitable focal length. A consistency check confirms that adding positive power via a convex lens shifts the near image forward onto the retina, restoring clear near vision.
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About This Question
- Subject
- physics
- Chapter
- optics
- Topic
- human eye and defects of vision
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
Hypermetropia, corrected with a converging convex lens
NCERT explains that hypermetropia, or far-sightedness, occurs when the eye's near point recedes beyond the normal 25 cm, so nearby objects form their image behind the retina because the eye's converging power is insufficient. Since distant vision remains clear, the defect specifically affects close work, exactly as described. The remedy is a converging convex lens, which adds the missing converging power so that near objects focus precisely on the retina. The option naming myopia with a concave lens is wrong because myopia is the opposite defect, where distant objects blur, not near ones. The option pairing hypermetropia with a concave lens is wrong because a diverging lens would worsen the shortfall in converging power. The option pairing myopia with a convex lens misidentifies both the defect and its correction. As stated in NCERT Class 12, Chapter 9, hypermetropia is corrected using convex lenses of suitable focal length. A consistency check confirms that adding positive power via a convex lens shifts the near image forward onto the retina, restoring clear near vision.
This medium difficulty physics question is from the chapter optics, covering the topic of human eye and defects of vision. It appeared in the 2025 exam.
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