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electronics circuits. The frequency of microwaves lies between 10-19 - 3 x 1011 Hz Hz. The microwaves are used in radar and other communication systems. Radiowaves. Like microwaves, radiowaves are also produced by oscillating electronic circuits. The frequency of radiowaves varies from a few Hz to 10-19 Hz. The radiowaves are used as carrier waves in radio broadcasting and TV transmission.
Electromagnetic Spectrum
Name
Frequency range (Hz) Wavelength range (m)
how produced
Gamma-X-rays X-rays
5 x 1020 - 3 x 1019 3 x 10-19 10-16
6x 10-13 . 10-10 1x 10-10 - 3 x 10-8
1016 - 8 x 1014
3 x 10-.4 x 10-2
Ultra-Violet rays (UV) Visible light
8 x 1024.4x1014
4 x 10-7-8 x 10-7
Nuclei of atoms. Bombardment of high Z target by electrons. Excitation of atoms and vacuum spark Excitation of atoms, spark and are flame Excitation of atoms and molecules Heating Oscillating currents in special vacuum tubes. Oscillating circuits.
Infra-Red rays (IR) 4x 101 - 1013
8 x 102 - 3 x 10-5
Heat radiation Microwaves
3 x 1013 - 3 x 109 3x 10-10°
10-5-10-1 10-3 - 3 x 10
10-1
1-10
Oscillating circuits.
Ultra High radio 3 x 10' - 3x108 Frequencies (UHF) Very High radio 3 x 108 - 3x10? Frequencies (VHF) Radio frequencies 3 x 107 - 3x10 Power frequencies 60-50
10-104 5 x 10' - 6 x 106
Oscillating circuits. Weak radiation from a.c. ciurcuits
57. Satish K. Gupta, op. cit, p. 739 —
"Infra-red rays were discovered by Herschell. Infra-red rays are heat radiation and therefore all hot bodies are the sources of infra-red rays. About 60% of the solar radiation is infra-red in nature. Following are a few sources to produce infra-red rays. 1. Nernst lamp. The filament of Nernst lamp is made from the mixture
of ziroconium, thorium and cerium. When a current is passed through such a filament, then at a temperature of about 1200 K, infra-red rays are emitted. Globar. It is basically a rod of silicon carbode. Which when heated to a temperature of about 900 K by passing current, produces infra-red rays.
102
TAHT YFI sich 120-121
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