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Science · 2026 · 3 marks
CBSE 2026 · Region 2 · Set 3 · Q35
(a)Write the name of the lens and position of the object in front of it so that a virtual and magnified image is formed.(b)An object is placed perpendicular to the principal axis of a convex lens of focal length $\displaystyle 20$ cm. If object is located at $\displaystyle 30$ cm from this lens, using lens formula find out the position and nature of the image formed.
(a)
Write the name of the lens and position of the object in front of it so that a virtual and magnified image is formed.
(b)
An object is placed perpendicular to the principal axis of a convex lens of focal length $\displaystyle 20$ cm. If object is located at $\displaystyle 30$ cm from this lens, using lens formula find out the position and nature of the image formed.
Marking-scheme solution
(a)
Convex lens
When object is placed between focus and optical centre
(b)
\(\displaystyle \mathrm{f}=+20 \mathrm{~cm} \mathrm{u}=-30 \mathrm{~cm}\)
\[\begin{aligned}
& \frac{1}{v}-\frac{1}{u}=\frac{1}{f} \\
& \frac{1}{v}=\frac{1}{f}+\frac{1}{u} \\
& \frac{1}{v}=\frac{1}{20}+\frac{1}{-30} \\
& \frac{1}{v}=\frac{1}{60} \\
& v=60 \mathrm{~cm}
\end{aligned}
\]
The image is formed at a distance of $\displaystyle 60$ cm on the other side of the optical centre.
Nature of image - Real, inverted
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CBSE Class 10 Science past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.