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Science · 2024 · 2 marks
CBSE 2024 · Region 2 · Set 3 · Q25
(a) A person suffering from an eye defect uses lenses of power -1 D. Name the defect of vision and list its two causes. State the nature…
(a)
A person suffering from an eye defect uses lenses of power -$\displaystyle 1$ D. Name the defect of vision and list its two causes. State the nature (converging/diverging) of the corrective lens.
OR
(b)
What is presbyopia ? Name the type of lenses used for the correction of this defect. State the nature (converging/diverging) of the upper part of such lenses.
Marking-scheme solution
Myopia
Two causes :
Excessive curvature of eye lens Elongation of eye ball
Diverging lens
The power of accommodation of eye lens usually decreases with ageing and the person finds it difficult to see nearby objects comfortably and distinctly.
Convex lens (Bifocal lens if the person has myopia also.)
The upper part of bifocal lens will be diverging.
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CBSE Class 10 Science past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.