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Science · 2024 · 2 marks
CBSE 2024 · Region 4 · Set 1 · Q25
A person suffering from presbyopia needs bifocal lens. If he needs two lens of power - $\displaystyle 4 \cdot 0$ dioptre and $\displaystyle +2 \cdot 0$ dioptre, which one of these two lenses is for the correction of distant vision and what is its focal length ?
Marking-scheme solution
For distant vision: lens of power - \(\displaystyle 4 \cdot 0\) dioptre
\(\displaystyle \mathrm{f}(\) meter \(\displaystyle )=\frac{1}{P}=\frac{1}{-4 \cdot 0 D}=-0.25 \mathrm{~m}\) or -$\displaystyle 25$ cm
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CBSE Class 10 Science past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.