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Physics · 2025 · 3 marks
CBSE 2025 · Region 2 · Set 1 · Q26
(a) When a parallel beam of light enters water surface obliquely at some angle, what is the effect on the width of the beam? (b) With the help of a…
(a)
When a parallel beam of light enters water surface obliquely at some angle, what is the effect on the width of the beam?
(b)
With the help of a ray diagram, show that a straw appears bent when it is partly dipped in water and explain it.
(c)
Explain the transmission of optical signal through an optical fibre by a diagram.
Marking-scheme solution
(a)
Width of the parallel beam of light increases in water.
(b)
Due to refraction of light, the image of the portion immersed in water appears to be raised.
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CBSE Class 12 Physics past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.