electromagnetic spectrum


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electromagnetic spectrum

See electromagnetic radiation.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

electromagnetic spectrum

[i¦lek·trō·mag′ned·ik ′spek·trəm]
(electromagnetism)
The total range of wavelengths or frequencies of electromagnetic radiation, extending from the longest radio waves to the shortest known cosmic rays.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

electromagnetic spectrum

electromagnetic spectrumclick for a larger image
electromagnetic spectrumclick for a larger image
electromagnetic spectrumclick for a larger image
electromagnetic spectrumclick for a larger image
The ordered array of known electromagnetic radiation, extending from the shortest cosmic rays, through gamma rays, X-rays, ultraviolet radiation, visible radiation, and infrared radiation. It includes microwave and all other wavelengths of radio energy. See the illustration for a more detailed view of this spectrum.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

spectrum

The range of electromagnetic radiation (electromagnetic waves) in our known universe, which includes visible light. The radio spectrum, which includes both licensed and unlicensed frequencies up to 300 GHz has been defined worldwide in three regions: Europe and Northern Asia (Region 1); North and South America (Region 2), and Southern Asia and Australia (Region 3). Some frequency bands are used for the same purpose in all three regions while others differ. See satellite frequency bands and optical bands.

Higher Frequencies
Frequencies above 40 GHz have not been licensed, but are expected to be made available in the future as the technology is developed to transmit at these smaller wavelengths (higher frequencies). The spectrum can be viewed in meticulous detail from the Federal Communications Commission (FCC) and National Telecommunications and Information Administration (NTIA) by visiting www.fcc.gov/oet/spectrum and www.ntia.doc.gov/osmhome/osmhome.html. See electromagnetic radiation and wave.

Should Airwaves Be Licensed?


There is a great deal of controversy over the licensing of frequencies. In Kevin Werbach's very educational white paper, "Radio Revolution," the author says an artificial scarcity has been created because policy makers do not understand the technology. He states that many believe the traditional policy of dividing the airwaves into licensed bands now impedes progress because today's radio technologies allow for much more sharing of the spectrum than ever before. The old notion that radio waves interfere with and cancel each other is a false one. Waves just mix together and become more difficult to differentiate, but modern electronics can, in fact, separate them.

To obtain a copy of this insightful report written in 2003, as well as other related articles, visit Werbach's website at www.werbach.com. See smart radio.


Visible Light
Our eyes perceive a tiny sliver of the electromagnetic spectrum. The wavelengths from (approximately) 400 to 750 nanometers provide us with our physical view of the universe.





Visible Light
Our eyes perceive a tiny sliver of the electromagnetic spectrum. The wavelengths from (approximately) 400 to 750 nanometers provide us with our physical view of the universe.
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References in periodicals archive ?
"We've created approaches that open a previously untapped portion of the electromagnetic spectrum for consumer use and life-saving medical applications," said Dr.
Waves in the electromagnetic spectrum are arranged in order of wave.
The definition of Cyberspace must be broad enough to enable us to integrate the vast possibilities that the electromagnetic spectrum offers now and for the future.
Flying the EA-6B Prowler, conducts airborne electronic warfare including electronic attack/protection/support to control the electromagnetic spectrum or to attack the enemy in support of Fleet Marine Force and joint operations.
The infrared energy that is radiated in the invisible portion of the electromagnetic spectrum is sensed by a non-contacting IR sensor that is trained on the part in the work station.
GLAST is a NASA satellite planned for launch in 2006 that detects gamma rays, the highest energy light in the electromagnetic spectrum. This guide provides three hands-on activities to help students understand how the universe is studied and explored through the use of GLAST.
Scientists from Leeds University in the UK have developed a device which utilises terahertz waves - between microwaves and infra red on the electromagnetic spectrum - to 'see through' solid materials.
It's not far from what the novelist Andrew Nelson Lytle had in mind when, in the '30s, he instructed his fellow Southerners to "throw out the radio and take down the fiddle from the wall." There have been times when doing free radio has meant evading the electromagnetic spectrum altogether, as with the Jamaican soundtracks that played music beloved in the island's poor communities but absent from the official airwaves; or the street DJs who invented hip-hop, mixing disks with a ferocious eclecticism that would have shocked even the most experimental freeform disc jockey of the hippie days.
The energies measured and studied are in the electromagnetic spectrum, wh ich includes infrared, visible, and ultraviolet light; geomagnetic and electromagnetic fields; and vibration.
Researchers at NIST have demonstrated the effectiveness of photostimulable image plates for recording spectra in the far ultraviolet region of the electromagnetic spectrum. Although image plates have been used for higher energy applications such as x-ray crystallography, no one previously had evaluated them for far UV spectroscopy.
Light that is visible to the human eye occupies an extremely small part of the electromagnetic spectrum. This confluence of the visible spectrum, the structure of the human eye and entire perceptual system is in itself a miraculous synthesis.
(DBS is sometimes known as L-Band, the portion of the electromagnetic spectrum with frequencies between 950-2,150 MHz.)

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