| 单词 | Table E-4: Frequency Spectrum: Band Designations, Nominal Frequency Ranges, Nominal |
| 释义 | Table E-4: Frequency Spectrum: Band Designations, Nominal Frequency Ranges, Nominal Wavelengths, and Example Communications Applications (continued) Band Designation Frequency (Hz)1 Wavelength ( )2 Applications Ultraviolet Light (UV) 1 PHz – 30 PHz 380 nm – 10 nm Not Applicable X-Rays 30 PHz – 30 EHz 10 nm – .01 nm Not Applicable Gamma and Cosmic Rays >3 EHz <.1 nm Not Applicable 1k = kilo = 1,000 (1 thousand) 1M = Mega = 1,000,000 (1 million) 1G = Giga = 1,000,000,000 (1 billion) 1T = Tera = 1,000,000,000,000 (1 trillion) 1P = Peta = 1,000,000,000,000,000 (1 quadrillion) 1E = Exa = 1,000,000,000,000,000,000 (1 quintillion) 2km = kilometer (1,000 meters) 2m = meter 2cm = centimeter (1/100 meter) 2mm = millimeter (1/1,000 meter) 2µ = micron (1/1,000,000 meter) 2nm = nanometer (1/1,000,000,000 meter) The wavelength figures assume transmission in a vacuum.Wavelength in a medium will be shorter due to the fact that the frequency remains the same while the signal propagates at speeds less than 300 km/s. For example, in glass the speed of light is reduced by the index of refraction, which is about 1.5 in practice, so the velocity of propagation (Vp) is approximately 200 km/s (300/1.5 = 200). Index of refraction (IOR) is the ratio of speed in a vacuum divided by speed in the medium. See also IOR, medium, vacuum, and Vp. |
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