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Explain the following, giving proper reason : (a) During charging of a capacitor, displacement current exists in the capacitor. But there is no displacement current when it gets fully charged. (b) The frequency of microwaves in ovens matches with the resonant frequency of water molecules. (c) Infrared waves are also known as heat waves.
How are X-rays produced? Give any two uses of these.
Name the electromagnetic waves which are produced by the following: (i) Radioactive decays of nucleus (ii) Welding arcs (iii) Hot bodies Write one use each of these waves.
Write two uses of any two of these radiation.
(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 ?
Electromagnetic waves of wavelengths λ₁, λ₂ and λ₃ are used in radar systems, in water purifiers and in remote switches of TV, respectively.
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