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All abot EMFs
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THE NATURE OF ELECTROMAGNETIC RADIATION
This tells you all you need to know about Electromagnetic radiation in its various forms—it’s a long read of about 8 of these pages. But persevere!
See here for an article on ‘Prudent Avoidance’ of EMFs, ElectroStress, electromagnetic radiation, etc. See here for a real picture of what high-tension lines can do… See here for an article on electrosensitivity See here for an article on cellphones
(From http://www.milligauss.com/info.html)
The Author:
Mr. George S. Lechter holds a BS in mechanical engineering from M.I.T. (1975) with a concentration in computers, and holds an MS degree from M.I.T.'s Sloan School of Management (1977). He has had 26 years of experience in the computer and electromagnetic field. He worked as a management consultant for Harbridge House, Inc. (then a Sears Roebuck company) and as a strategic market planning consultant for Braxton Associates in Boston. He was a minicomputer marketing specialist at Nixdorf in Waltham, MA, and worked in the software industry for 9 years. In 1988 he founded Technology Alternatives Corporation. Mr. Lechter holds several patents.
For a summary of what you can do in terms of prudent avoidance of EMR influences, go directly to the end of this article.
An AC electric current is defined as the movement of electrons in roughly the same direction, usually through a wire. This current, in turn, produces two types of fields: an AC electric field and an AC magnetic field, which together are called an electromagnetic field. The AC electric fields result from the strength of the charge and the AC magnetic fields result from the motion of the charge (i.e., the flow of electrons comprising the electric current). The AC electric field represents the force that electric charges exert on other charges, and this force may either repel (as with two positive charges, for example) or attract. The AC magnetic field forms a closed continuous doughnut-shaped loop around the current and radiates at a right angle to the direction of the current.
People can sense an electric field of more than about 20 kilovolts/meter (kV/m) as a slight tingling sensation on their skin. This level can be found underneath high voltage power lines. On the other hand, most people cannot feel the presence of AC magnetic fields except at extraordinarily strong levels (although some people claim they can sense even low levels of EMF).
Interestingly, while an AC electric current creates an AC magnetic field, it is also true that an AC magnetic field creates an AC electric current in a nearby conductor. This is the principle of induction, and it is how we detect and measure AC EMF fields. Induction is also the principle by which a transformer raises or lowers voltages. In a transformer, an AC electric current flowing through a coil of wire radiates an AC magnetic field, and another adjacent coil of wire picks up the AC magnetic field and converts it back into AC electric current. The number of coils on each side of the transformer determine by how much the voltage is increased or decreased.
In order to distribute electricity economically over long distances, high voltages are used. Between the power plant and your home, a series of transformers reduce the voltage along the way so that by the time it reaches your home, the voltage has been reduced to the 120/240 volt level. It is desirable to use alternating current (AC), since most transformers work only with AC. AC means that the direction of the current alternates back and forth. The frequency of the back and forth cycle is measured in Hertz (Hz), which stands for cycles per second. Hence, when we talk about a 60 Hz current, which is the standard in the United States, this means that the direction of the current is changing back and forth 60 times per second. In Europe and other parts of the world, the frequency of AC electric power is 50 Hz rather than 60 Hz.
A graph of AC current (voltage vs. time) will form a sine wave, with a positive voltage for half of the time, and a negative voltage for the other half. The same is true of the electric and magnetic fields, which travel in one direction and then the other, corresponding with the changes in direction of the AC current. Since power lines, household wiring and appliances all carry electricity with a 60 Hz cycle, the resulting AC electric and AC magnetic fields also oscillate at 60 Hz. Such frequencies are at the low end of the electromagnetic spectrum, and are referred to as extremely low frequency (ELF) fields. The 60 Hz frequency originates at the power generating station and ends up in our household appliances. Higher voltages change the strength of the fields, but not the 60 Hz frequency.
Radiation is a broad term meaning the transmission of energy in the form of waves through space or through a material medium and also the radiated energy itself. The force field associated with radiation is the region throughout which the radiation is measurable. Sometimes electromagnetic radiation is called EMR, while electromagnetic fields are frequently referred to as EMF. EMR and EMF refer to the entire range of the electromagnetic spectrum, from extremely low frequencies to radio waves. In practice, EMF is used more often than EMR because "radiation" sounds scary and its use may create confusion with more dangerous radiation from X-ray machines and radioactive material. In news reports and articles written for the general public (such as this article), EMF is used loosely to indicate the low frequency electromagnetic fields coming from power lines, home wiring, appliances, TVs and computer displays.
EMF from different sources can either add together or cancel each other out. This is due to the wave characteristics of electromagnetic radiation. If the radiation from two sources are in phase, then the peaks of each cycle will occur together, and the fields will add together. On the other hand, if the two sources are exactly out of phase, then one source will be reaching its greatest strength in one direction at exactly the same time as the other source is peaking in the opposite direction. If the magnitude of the fields is identical, then the fields will cancel each other out, and the magnetic field measurement will be zero. This is why neutral and hot wires in household wiring need to be paired close together. This characteristic also provides a mechanism for configuring power lines and VDTs so that EMF levels are reduced. EMF can be either man-made or occur naturally. Examples of electromagnetic radiation, in order of increasing frequency, are extremely low frequency (ELF), very low frequency (VLF), radio waves, microwaves, infrared (heat), visible light, ultraviolet, X-rays, and gamma rays. All electromagnetic radiation travels at the speed of light.
The frequency of the electromagnetic radiation is what determines its character. X-rays (and other forms of ionizing radiation) can strip electrons away from an atom, thereby creating an "ion." When living systems are exposed to such radiation, detrimental effects are caused by breaking apart molecular bonds. Cancer can be caused by such ionizing radiation when DNA (the molecules that make genes) is broken apart. At ELF frequencies, electromagnetic radiation is non-ionizing, meaning it cannot knock electrons away from atoms or alter molecular structures. However, low frequency electromagnetic radiation is nevertheless an energy force, and this energy force can shake atoms and molecules back and forth. The field strength of electromagnetic fields can be calculated mathematically.
Fields from compact sources containing coils or magnets (transformers, appliances, and computer displays, for example) diminish most rapidly with distance F in proportion with the distance cubed (1/d**3; d = distance). Fields from long wire conductors in power lines drop off in proportion with the distance squared (1/d**2), provided the currents flowing in opposite directions are well-balanced. The field strength drops off less quickly with secondary distribution lines, since the currents are frequently unbalanced. In practice, it is easier to measure the field strength than to calculate it, since there are usually multiple EMF sources which interact with each other in complex ways.
THEORIES ON HOW EMF AFFECTS BIOLOGICAL SYSTEMS
For many years some scientists and engineers felt that low frequency EMF could not possibly produce significant biological changes or effects. This reasoning was based upon the fact that low frequency EMF cannot break molecular bonds and it generates only a miniscule amount of heat - not enough to heat body tissue. However, this argument has turned out to be incorrect because there are other ways in which fields can interact with individual cells to produce biological changes.
If we recall that magnetic fields can induce an electric current in a nearby conductor, the implication is that AC magnetic fields will induce electric currents in our bodies (although such currents will be very small). That's because our bodies are mostly comprised of a conductive medium (salty water). Some of these currents are similar to what a salamander uses to regenerate a limb, and therefore the artificial creation of these currents in a human body are of concern.
The way in which electromagnetic radiation affects the body is not fully known. A similar state of knowledge applies to the mechanisms behind how aspirin cures a headache or |
