CBSE 2024 · Region 1 · Set 1 · Q26 · 3 marks
(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.(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 ?
(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.
(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.
(i)
Ionosphere reflects waves in these bands
(ii) Atmosphere absorbs x-rays, while visible and radio waves can penetrate it
Electromagnetic WavesElectromagnetic SpectrumUnderstandshort_answermedium
More from Electromagnetic Waves
- The ratio of amplitude of electric field to the amplitude of the magnetic field associated with an…2026 · asked 3×
- The magnetic field in a plane electromagnetic wave travelling in glass (n=1 · 5) is given by B y=(2 × 10^-7…2026 · asked 3×
- A plane electromagnetic wave travels through a medium and the magnetic field associated with it is given by…2026 · asked 3×
- How are infrared waves produced? Why are these waves referred to as heat waves? Give any two uses of infrared…2023 · asked 3×
- What is meant by the term 'displacement current'? Briefly explain how this current is different from a…2023 · asked 3×
- Identify electromagnetic waves which: (i) are used in radar system. (ii) affect a photographic plate. (iii)…2022 · asked 3×
- Which of the following electromagnetic waves has photons of largest momentum?2025 · asked 3×
- (i) Depict a plane electromagnetic wave propagating along the x-axis. Write the expressions for its…2022 · asked 3×
CBSE Class 12 Physics past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.