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Topic: Electromagnetic field

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  Electromagnetism - Wikipedia, the free encyclopedia
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, which exerts a force on those particles that possess the property of electric charge, and is in turn affected by the presence and motion of such particles.
A non-zero electric field is produced by the presence of electrically charged particles, and gives rise to the electric force; this is the force that causes static electricity and drives the flow of electric charge (electric current) in electrical conductors.
In classical electromagnetism, the electromagnetic field obeys a set of equations known as Maxwell's equations, and the electromagnetic force is given by the Lorentz force law.
en.wikipedia.org /wiki/Electromagnetism   (1172 words)

 Electromagnetic field - Wikipedia, the free encyclopedia
An electric field is produced when the charge is stationary with respect to an observer measuring the properties of the charge and a magnetic field (as well as an electric field) is produced when the charge moves (creating an electric current) with respect to this observer.
An alternative interpretation would be that the field is not actually a velocity field, but a flux density field of photonic fluid, which is constantly moving at the same speed: the speed of light, independent of the speed of the observer (the charged object).
The tensor character of this combined electromagnetic field implies that the field is anisotropic with respect to the velocity of the charged particle on which it produces a force: the Lorentz force varies with the velocity of the charged particle.
en.wikipedia.org /wiki/Electromagnetic_field   (1755 words)

 Magnetic field - Wikipedia, the free encyclopedia
Formally, the magnetic field is not a vector, it is a pseudovector.
Electromagnetic field - a field composed of two related vectorial fields, the electric field and the magnetic field.
Electromagnetism - the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field.
en.wikipedia.org /wiki/Magnetic_field   (1962 words)

 Electromagnetic Field Encyclopedia Article @ NaturalResearch.org   (Site not responding. Last check: 2007-10-22)
An electromagnetic field is composed of two related vector fields: the electric field and the magnetic field.
When referred to as the electromagnetic field, the field is imagined to encompass all of space; typically an electromagnetic field is considered to be limited to a local area around an object in space.
If the field were the velocity field of a fluid then the fluid would cause the object to accelerate continually in the direction of the fluid's motion, to the point that the object's speed becomes paradoxically far greater than that of the fluid is in which it is immersed.
www.naturalresearch.org /encyclopedia/Electromagnetic_field   (1866 words)

 Define electromagnetic field - a Whatis.com definition - see also: EM field
An electromagnetic field, sometimes referred to as an EM field, is generated when charged particles, such as electrons, are accelerated.
Electromagnetic fields were first discovered in the 19th century, when physicists noticed that electric arcs (sparks) could be reproduced at a distance, with no connecting wires in between.
Electromagnetic fields are typically generated by alternating current (AC) in electrical conductors.
searchsmb.techtarget.com /sDefinition/0,,sid44_gci212055,00.html   (428 words)

 Electromagnetic Radiation: Field Memo
Yet, electromagnetic radiation is exactly that, electrical energy moving through space as a wave, and electrical energy in a wire is a special case in which the energy is guided by a wire.
Since both the E field and the H field components of electromagnetic waves are absorbed by living tissue, and since the relationship between E and H is complicated in the near-field, we must measure both E and H when evaluating near-field hazards.
Ratio of the electric field (E) to the magnetic field (H), in the far-field this is the characteristic impedance of free space, 377 Ohms.
www.osha.gov /SLTC/radiofrequencyradiation/electromagnetic_fieldmemo/electromagnetic.html   (8300 words)

 The Earth's Magnetic Field
The field lines defining the structure of the magnetic field are similar to those of a simple bar magnet, as illustrated in the following figure.
Thus, true north (defined by the direction to the north rotational pole) does not coincide with magnetic north (defined by the direction to the north magnetic pole) and compass directions must be corrected by fixed amounts at given points on the surface of the Earth to yield true directions.
The origin of the Earth's magnetic field is not completely understood, but is thought to be associated with electrical currents produced by the coupling of convective effects and rotation in the spinning liquid metallic outer core of iron and nickel.
csep10.phys.utk.edu /astr161/lect/earth/magnetic.html   (585 words)

 Electromagnetic Field Detector   (Site not responding. Last check: 2007-10-22)
This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer.
Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields.
The field that surrounds a transformer is heard as a 50 or 60Hz buzz.
www.mitedu.freeserve.co.uk /Circuits/Misc/emf.htm   (299 words)

 WHO | What are electromagnetic fields?
Electromagnetic fields are present everywhere in our environment but are invisible to the human eye.
The earth's magnetic field causes a compass needle to orient in a North-South direction and is used by birds and fish for navigation.
Man-made sources of electromagnetic fields that form a major part of industrialized life - electricity, microwaves and radiofrequency fields – are found at the relatively long wavelength and low frequency end of the electromagnetic spectrum and their quanta are unable to break chemical bonds.
www.who.int /peh-emf/about/WhatisEMF/en   (1685 words)

 The cemi field theory
The second is that the brain’s em field is indeed the seat of consciousness.
Synchronous firing and its influence on the brain's electromagnetic field: evidence for an electromagnetic theory of consciousness.
The em field outside the head is far too weak and it is highly unlikley that any other brain could detect it, and still more unlikely that the other brain could decode the em field information that was encoded by your brain (which i think is a good thing).
www.surrey.ac.uk /qe/cemi.htm   (1578 words)

 Natural Electromagnetic Meter
Ball lightning should in theory be associated with a strong magnetic field, and magnetization of metal on the ground has been reported with some sightings of unusual lights in the sky.
A 3V/m field is so feeble that if a 10'x10'x10' room were filled with a field of this strength, it would contain the total amount of energy equivalent to that required to lift a single grain of table salt 1/50th of an inch.
Clearly the static electric field is the type that requires the least energy to be detectable.
www.trifield.com /EMF_natural.htm   (1019 words)

 Electromagnetic field at opensource encyclopedia   (Site not responding. Last check: 2007-10-22)
The electromagnetic field generates a force F on a charged particle, given by the Lorentz equation
However, the force of an electric field on a charged particle is \mathbf{F} = q \mathbf{E} , and this force is independent of the velocity of the particle, which means that the particle will accelerate continually in the direction of the field.
Phenomena in the list are marked with a star (\star) if they consist of magnetic fields and moving charges which can be reduced by suitable Lorentz transformations to electric fields and static charges.
www.wiki.tatet.com /Electromagnetic_field.html   (1736 words)

 Electromagnetic Field Theory Internet Textbook
Written with the advanced undergraduate or graduate student in mind, Electromagnetic Field Theory is a textbook on the theory of electrodynamics, at roughly the same level as the well-known textbooks by Jackson and Panofsky&Phillips.
It treats relativistic covariance and the Lagrangian/Hamiltionan formulation of electromagnetic field theory, with an eye on modern ideas of duality and unification of theories, and includes a rigorous, comprehensive and detailed treatment of EM radiation phenomena and some elements of semiclassical quantum electrodynmaics.
Electromagnetic Field Theory is intended as an Internet source which is freely available to physics students, at the advanced undergraduate or beginning graduate level, and research workers anywhere.
www.plasma.uu.se /CED/Book   (974 words)

 ipedia.com: Electromagnetic field Article   (Site not responding. Last check: 2007-10-22)
The electromagnetic field is composed of two related vectorial fields, the electric field and the magnetic field.
This means that the vectorss (E and B) that characterize the field each have a value defined at each point of space and time.
However, the force of an electric field on a charged particle is, and this force is independent of the velocity of the particle, which means that the particle will accelerate continually in the direction of the field.
www.ipedia.com /electromagnetic_field.html   (1681 words)

 Electromagnetic Field Sensitivity
The major emphasis of this phase of the studies was the evaluation of the effects of the magnetic field generated by a coil fed from a sweep/function generator (Model 3030, B.K. Precision Dynascan Corp.).
Some patients reacted to the fields generated by the fluorescent lights, and others did not present the same signs and symptoms at each challenge, even though the reactions were significant when contrasted with the blank responses.
As a result of the weak field levels and short exposure time, the responses were mild except in two patients whose symptoms were so severe (e.g., drop attack, severe itching) that they received intravenous vitamin C, magnesium, and oxygen as a result of the prolonged and delayed reactions.
www.aehf.com /articles/em_sensitive.html   (2925 words)

 BBC NEWS | Health | Electromagnetic field 'creates toxic gas'
Researcher Dr Steve Goheen said that it could be an interaction between the magnetic field created near the ioniser and the water found naturally in the body of the rat.
He said there was no particular reason to believe a human exposed to a similar field would not produce their own personal ozone cloud as well.
Other studies have focused on the possibility that electromagnetic fields may encourage higher concentrations of pollutants to gather in houses directly under their path.
news.bbc.co.uk /2/hi/health/3472383.stm   (562 words)

 Electromagnetic Field Theory Group at IFH
It is our pleasure to welcome you to the Electromagnetic Field Theory Group at the Laboratory for Electromagnetic Fields and Microwave Electronics (IFH).
Field Theory or Electromagnetics is a discipline that describes the behavior of electric and magnetic fields and their sources in a specific environment.
Thus a continuous physical reality, the electromagnetic field, is represented by a discretized, sampled numerical approximation to replicate the behavior of the actual problem with appropriate accuracy and resolution.
www.ifh.ee.ethz.ch /Field   (166 words)

EMF protection is afforded by the Teslar wristwatch, manufactured by ELF International, the same company responsible for the development of the Light Beam Generator (see "Shedding Light on Lymphatic Health," Alternative Medicine magazine, May, 2000).
Named after Nikola Tesla, the inventor of alternating current and "father" of the technology it employs, the Teslar Watch produces its own energy field in the form of a "scalar wave," which has been shown to screen other ELF signals.
According to Valerie Hunt, Ph.D., and Professor Emeritus at UCLA, a renowned researcher of the human bioenergy field, scalar energy is created when two identical frequencies meet head on from opposite directions, canceling each other out to leave a stationary energy.
www.angelfire.com /md/Miraclemaker/EMFs.html   (205 words)

 Maxwell’s Electromagnetic Field Equations   (Site not responding. Last check: 2007-10-22)
The result showed that the speed of propagation was equal to the speed of light, which indicated that light is also an electromagnetic field.
Maxwell’s equations are the bases for the theory of electromagnetic fields and waves.
The calculus required for the derivations and problems is presented in detail to remove the difficulties of the mathematics from being an impediment to the students in making the equations their own.
www.iit.edu /~smile/guests/gsmxint.htm   (261 words)

 Open Directory - Science: Environment: Energy: Electromagnetic Field
Electromagnetic Safety Network - Covers the distinction between natural and artificially created electromagnetic fields.
Magnetic field measurement - Our main activity is centered around precise magnetic field and gradient measurement and its various applications in biomagnetism.
Static EM Fields and Cancer FAQ - Reviews the laboratory and epidemiological evidence relevant to whether static (direct current, DC) magnetic or electric fields contribute to cancer in humans.
dmoz.org /Science/Environment/Energy/Electromagnetic_Field   (715 words)

 Pulsed Magnetic Therapy: Pulsed Electromagnetic Field Therapy (PEMF Therapy) Research Review.
EarthPulse® pulsed electromagnetic field video testimonials / case studies showing substantially enhanced performance, are not intended to suggest or imply that you will achieve similar results, but you'll have a full 90 days to try it risk free to see for yourself.
The magnetic field of the planet (and its pulsed magnetic component) is weakening and being overshadowed by electromagnetic man-made pollution.
These testimonials are not intended to recommend pulsed electromagnetic field therapy device as a drug or as a diagnosis for any illness or disease condition; nor, as a product to eliminate disease or other medical conditions.
www.earthpulse.net   (3545 words)

 ARRLWeb: RF Radiation and Electromagnetic Field Safety
But in the last 100 years, man-made fields at much higher intensities and with a very different spectral distribution have altered this natural EM background in ways that are not yet fully understood.
Because these fields dissipate rapidly with distance, "prudent avoidance" would mean staying perhaps 12 to 18 inches away from most Amateur Radio equipment (and 24 inches from power supplies with 1-kW RF amplifiers) whenever the ac power is turned on.
Unfortunately, determining the power density of the RF fields generated by an amateur station is not as simple as measuring low-frequency magnetic fields.
www.arrl.org /news/rfsafety/hbkrf.html   (4588 words)

 The Electromagnetic tensor
the electric and magnetic fields  are given by
in an electromagnetic field is [ Assignment 4 ]:
This is the energy momentum tensor of the electromagnetic field.
www.mth.uct.ac.za /omei/gr/chap4/node7.html   (168 words)

 Trifield Electromagnetic Field Meter
Evidence indicates that electric and magnetic fields from high tension wires, CRT computer screens, microwave ovens, and other household appliances increase the risk of certain cancers and other physiological and psychological abnormalities.
Based on epidemiological studies, personal exposure to electromagnetic pollution should be avoided if it produces AC currents inside the body higher than the threshold level, of frequencies at or below 1000 cycles per second.
The Magnetic and Electric field selectors are calibrated for typical 60-cycle power-line frequencies (A 50-cycle version typical for overseas power systems is available upon request), while the Radio/Microwave detector is calibrated for the peak frequencies of home microwave ovens, at 2000 MHz.
www.orgonelab.org /ytrifield.htm   (854 words)

 Our Conscious Mind Could Be An Electromagnetic Field
Are our thoughts made of the distributed kind of electromagnetic field that permeates space and carries the broadcast signal to the TV or radio.
The brain's em field does the binding that is characteristic of consciousness.
The brain's electromagnetic field is not just an information sink; it can influence our actions, pushing some neurons towards firing and others away from firing.
unisci.com /stories/20022/0516026.htm   (853 words)

 Electromagnetic Field Probe with Meter Output   (Site not responding. Last check: 2007-10-22)
The output signal from the op-amp is an ac voltage at the frequency of the electro-magnetic field.
This was not directly from ripple on the power supply as it was regulated and well smoothed.What I had done was built the audio circuit on a small piece of veroboard, and placed it within a distance that was less than the diameter of the transformer.
The transformers own electromagnetic field was responsible for the induced noise and hum.
www.mitedu.freeserve.co.uk /Circuits/Testgear/emmeter.htm   (406 words)

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