electromagnetic spectrum Hear it!

electromagnetic spectrum Definition

electromagnetic spectrum

noun

the complete range of frequencies of electromagnetic waves from the lowest to the highest, including, in order, radio, infrared, visible light, ultraviolet, X-ray, and gamma ray waves

electromagnetic spectrum Telecom Definition

The full range of electromagnetic energy that can be radiated, as defined by frequency (f), or wavelength , which is the inverse of frequency. In terms of frequency, the spectrum begins at almost zero (0) and extends to infinity. In terms of wavelength, the spectrum begins at almost zero and extends to infinity, but in reverse.The portion of the spectrum currently usable for telecommunications includes electricity, radio, and infrared light. Table E-4 includes frequency band designations, nominal frequency ranges, nominal wavelengths, and example telecommunications applications.
Table E-4: Frequency Spectrum: Band Designations, Nominal Frequency Ranges, Nominal Wavelengths, and Example Communications Applications
Band DesignationFrequency (Hz)1Wavelength2Applications
Audible20 Hz ­ 20 kHz>100 kmAcoustics
Extremely Low Frequency (ELF) Radio30 Hz ­ 300 Hz10,000 km ­ 1,000 kmSubmarine Communications
Infralow Frequency (ILF)300 Hz ­ 3 kHz1,000 km ­ 100 kmNot Applicable
Very Low Frequency (VLF) Radio3 kHz ­ 30 kHz100 km ­ 10 kmNavigation, Weather
Low Frequency (LF) Radio30 kHz ­ 300 kHz10 km ­ 1 kmNavigation, Maritime Communications, Information and Weather Systems, Time Systems
Medium Frequency (MF) Radio300 kHz ­ 3 MHz1 km ­ 100 mNavigation, AM Radio, Mobile Radio
High Frequency (HF) Radio3 MHz ­ 30 MHz100 ­ 10 mCitizens Band (CB) Radio (aka Shortwave Radio), Mobile Radio, Maritime Radio
Very High Frequency (VHF) Radio30 MHz ­ 300 MHz10 m ­ 1 mAmateur (Ham) Radio, VHF TV, FM Radio, Mobile Satellite, Mobile Radio, Fixed Radio
Ultra High Frequency (UHF) Radio300 MHz ­ 3 GHz1 m ­ 10 cmMicrowave, Satellite, UHF TV, Paging, Cordless Telephony, Cellular and PCS Telephony, Wireless LAN
Super High Frequency (SHF) Radio3 GHz ­ 30 GHz10 cm ­ 1 cmMicrowave, Satellite, Wireless LAN
Extremely High Frequency (EHF) Radio30 GHz ­ 300 GHz1 cm ­ 1 mmMicrowave, Satellite, Radiolocation
Infrared Light (IR)300 GHz ­ 400 THz1 mm ­ 750 nmWireless LAN Bridges, Wireless LANs, Fiber Optics
Visible Light400 THz ­ 1 PHz750 nm ­ 380 nmNot Applicable
Ultraviolet Light (UV)1 PHz ­ 30 PHz380 nm ­ 10 nmNot Applicable
X-Rays30 PHz ­ 30 EHz10 nm ­ .01 nmNot Applicable
Gamma and Cosmic Rays>3 EHz<.1 nmNot Applicable
1 k = kilo = 1,000 (1 thousand) 1 M = Mega = 1,000,000 (1 million) 1 G = Giga = 1,000,000,000 (1 billion) 1 T = Tera = 1,000,000,000,000 (1 trillion) 1 P = Peta = 1,000,000,000,000,000 (1 quadrillion) 1 E = Exa = 1,000,000,000,000,000,000 (1 quintillion) 2 km = kilometer (1,000 meters) 2 m = meter 2 cm = centimeter (1/100 meter) 2 mm = millimeter (1/1,000 meter) 2 µ = micron (1/1,000,000 meter) 2 nm = 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.

electromagnetic spectrum Usage Examples

Converse of object

  • know: SOHO allows us to view the Sun in the part of the electromagnetic spectrum known as the extreme ultraviolet.
  • call: The family of electromagnetic waves from the high-frequency gamma rays to the relatively low-frequency radio waves forms what is called the electromagnetic spectrum.

Adjective modifier

entire: While control of the entire electromagnetic spectrum is impossible, key portions must be commanded at the right time.