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Physics · 2026 · 3 marks
CBSE 2026 · Region 1 · Set 1 · Q27
(a) Draw the ray diagram to show the image formation by a refracting telescope and write the expression for angular magnification for the telescope…
(a)
Draw the ray diagram to show the image formation by a refracting telescope and write the expression for angular magnification for the telescope in normal adjustment.
(b)
Give two reasons to explain why a reflecting telescope is preferred over a refracting telescope.
Marking-scheme solution
(a)
$\displaystyle |m|=\dfrac{f_{0}}{f_{e}}$
(b)
Reasons:
(i)
No Chromatic aberration
(ii)
Less mechanical support is required to install it.
(iii)
Image formed is brighter and clear.
(iv)
Cost efficient.
(v)
No / less Spherical aberration
[Any two reasons]
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CBSE Class 12 Physics past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.