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Physics · 2024 · 3 marks
CBSE 2024 · Region 1 · Set 1 · Q26
(a) "The wavelength of the electromagnetic wave is often correlated with the characteristic size of the system that radiates." Give two examples to…
(a)
"The wavelength of the electromagnetic wave is often correlated with the characteristic size of the system that radiates." Give two examples to justify this statement.
(b)(i)
Long distance radio broadcasts use short-wave bands. Why ?
(ii)
Optical and radio telescopes are built on the ground, but X-ray astronomy is possible only from satellites orbiting the Earth. Why ?
Marking-scheme solution
(a)
Gamma radiation having wavelength of \(\displaystyle 10^{-14} \mathrm{~m}\) to \(\displaystyle 10^{-15} \mathrm{~m}\), typically originate from an atomic nucleus.
X-rays are emitted from heavy atoms.
Radio waves are produced by accelerating electrons in a circuit. A transmitting antenna can most efficiently radiate waves having a wavelength of about the same size as the antenna.
(b)(i)
Ionosphere reflects waves in these bands
(ii) Atmosphere absorbs x-rays, while visible and radio waves can penetrate it
All Electromagnetic Waves questions2024 question paperNCERT solutions: Electromagnetic WavesPractice Electromagnetic Waves →
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CBSE Class 12 Physics past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.