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electromagnetic field good or bad


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#1 nec209

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Posted 3 March 2009 - 12:52 AM

Why do people call electronic devices or electrical devices radio frequency or part of the spectrum when it is not Radio,Microwave,Infrared,Visible, Ultraviolet,X-rays ,Gamma rays.:confused:

I know every electronic devices when turn on or electrical devices when turn on have Electromagnetic field or any electric current have a Electromagnetic field .

I know if the electromagnetic field is strong it can cause interference.That is why some times radios get interference from power lines ,cell towers ,electric saw if the electromagnetic field is strong.Any electronic devices or electrical devices cause interference if the electromagnetic field is strong.

But can EMF do harm to the body or get cancer ?Are EMF bad for people.What is SAR ??:eek:
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#2 insane_alien

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Posted 3 March 2009 - 08:30 AM

electronic devices do emit radiowaves. this is simply because the changing currents in the wires inside act like antennas. usually these radiowaves don't make it out of the casing but some do. this can cause interference with recievers(like on your telly).

powerlines also emit radio waves in massive quantities(at 50 or 60Hz depending on your location) as they also act like massive antennas.

EMF at levels produced by consumer electronics are generally not harmful(unless you jerry rig your microwave open while it reamins on, then you'll be cooked from the inside) and won't cause cancer.

sunbeds are the one exception to this as they emit UV which is capable of causing skin cancer with prolonged exposure(just like if you stood around on sunny days all day every day with no protection).

everything above UV has the potential to cause cancer with prolonged exposure. this happens only rarely and is why X-Ray machine operators have to wear the lead aprons and get behind the big screens because they get exposed fairly often.

pretty much everything below that is safe as long as the radiation isn't intense enough and in a wavelength where your body can absorb it. if it is it will cause heat damamge(burns, hyperthermia).

however, 99% of the spectrum just passes straight through you
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#3 swansont

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Posted 3 March 2009 - 11:11 AM

What is SAR ??


http://en.wikipedia....absorption_rate
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#4 nec209

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Posted 3 March 2009 - 11:41 AM

electronic devices do emit radiowaves. this is simply because the changing currents in the wires inside act like antennas. usually these radiowaves don't make it out of the casing but some do. this can cause interference with recievers(like on your telly).


powerlines also emit radio waves in massive quantities(at 50 or 60Hz depending on your location) as they also act like massive antennas.


By changing currents you mean AC ? So only electronic devices or electrical device we changing currents AC ?



pretty much everything below that is safe as long as the radiation isn't intense enough and in a wavelength where your body can absorb it. if it is it will cause heat damamge(burns, hyperthermia).

however, 99% of the spectrum just passes straight through you


Can you or someone elaborate that quote.
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#5 insane_alien

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Posted 3 March 2009 - 05:29 PM

By changing currents you mean AC ? So only electronic devices or electrical device we changing currents AC ?


yes, AC but also in DC systems when a switch is thrown or the voltage changes.

Can you or someone elaborate that quote.


well, there are two things that will determine how the EM radiation will affect you.

1/ Wavelength, basically the type of radiation(microwave, blue, red, Gamma, etc.) this determines how the radiation will affect you because how well your body absorbs the radiation depends on wavelengths.

The amount of energy carried in a photon of the radiation isalso wavelength dependant.

if the wavelength is small enough it can cause molecules to break appart if it hits them. This gets very serious if it impacts DNA. its this action that causes cancers, when the DNA becomes fragmented and broken due to absorption of a photon.

most long wavelength bands of EM radiation however just pass us by with no effect whatsoever. A specific microwave band that is absorbed by water can be dangerous due to the fact that it can heat us from the inside(like the food in your microwave).

2/ Intensity; intensity is the number of photons hitting you at one time.
if the intensity is very low its not really going to do much to you no matter what it is, if the intensity is high then it will either cause heating(for the longer wavelengths) or it will cause intracellular damage(for the shorter more penetrating wavelengths).

If the radiation passes by you with little to no effect then intensity doesn't matter, its not going to do anyhting to you either way.

if your body can absorb the radiation then intensity determines how quickly it will cause damage.

Lets take light as an example. i have a 10W bulb, a 100W bulb, a welding torch , a spot light and a nuclear blast.

the 10W bulb is low intensity, its not going to do anything to you and you can look at it without hurting your eyes. a 100W bulb is more intense and it'll hurt your eyes to stare at it for a bit.

a welding torch is even more intense, looking at this can make you go blind and standing near it can cause burns if unprotected.

The spotlight will instantly blind you if you look directly in it and you will experience burns if you stand close to it for a while.

the nuclear blast is the most intense(in my samples) and can vapourise you just with EM radiation from many kilometers away.
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#6 Kaeroll

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Posted 3 March 2009 - 05:31 PM

Frequency is proportional to energy - photons of high frequency have high energy and vice-versa. Radio waves are very low frequency, whereas UV is quite high. UV and higher frequency light have sufficient energy to break chemical bonds in your body and cause damage to your DNA, which is what can cause cancer. Radio frequencies (which are lower energy than visible light - you don't get cancer on your retina every time you open your eyes, do you?) are too low energy for this to happen.

What insane_alien is saying is that RF waves don't interact with your body significantly, and even frequencies that can (such as microwaves) are generally not intense enough to cause any real damage.
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#7 nec209

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Posted 15 March 2009 - 04:02 AM

From my understanding it is the type of electromagnetic radiation and intensity and the duration of exposure .

The type of electromagnetic radiation being the wavelength band.

The intensity being how strong the EMF is :eek: A radio trasmitting at 80 watts is not strong but a radio trasmitting at 500 watts is vey strong.

The Ultraviolet,X-rays ,Gamma rays are bad type of electromagnetic radiation do to cell damage.

Other types of electromagnetic radiation cannot cause cell damage.

The short wavelength have alot of energy it holds and the long wavelength have less energy ..

I think most EMF are good if the trasmitting power is low .But I do not want to get job at a power station or MRI tech.
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#8 nec209

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Posted 31 March 2009 - 12:07 AM

Who deleted my post? Anyways here was my post that should have got posted.

Gamma, x-ray and UV are classed as ionizing radiation. Ionizing radiation can cause cell damage by causing cancers and genetic damage as well as skin burns.

However, lower energy photons can also cause damage to cells and to the body in general, through different mechanisms.

The body usually doesn't respond to magnetic fields. It does respond to electric fields

High concentration electromagnetic radiation is not good for you.The stronger the current the stroger the electromagnetic field ans that is bad .

Here is one from wikipdia

Electromagnetic radiation can be classified into ionizing radiation and non-ionizing radiation, based on whether it is capable of ionizing atoms and breaking chemical bonds. Ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing. These pose their own special hazards: see radiation and radiation poisoning.

Non-ionizing radiation, discussed here, is associated with two major potential hazards: electrical and biological. Additionally, induced electric current caused by radiation can generate sparks and create a fire or explosive hazard

.

We are talking about biological so I will skip the electrical part.

The best understood biological effect of electromagnetic fields is to cause dielectric heating. For example, touching or standing around an antenna while a high-power transmitter is in operation can cause severe burns. These are exactly the kind of burns that would be caused inside a microwave oven.

This heating effect varies with the frequency of the electromagnetic energy. The eyes are particularly vulnerable to RF energy in the microwave range, and prolonged exposure to microwaves can lead to cataracts.[citation needed] Each frequency in the electromagnetic spectrum is absorbed by living tissue at a different rate, called the specific absorption rate or SAR, which has units of watts per kilogram (W/kg). The IEEE[3] and many national governments have established safety limits for exposure to various frequencies of electromagnetic energy based on SAR, mainly based on ICNIRP Guidelines[4], which are guarding against thermal damage.

There are publications which support the existence of complex biological effects of weaker non-thermal electromagnetic fields (see Bioelectromagnetics), including weak ELF magnetic fields[5][6] and modulated RF and microwave fields[7][8]. Fundamental mechanisms of the interaction between biological material and electromagnetic fields at non-thermal levels are not fully understood[9].

The definite existence and possible extent of non-thermal effects is not fully established. The chairman of the United Kingdom's Health Protection Agency (HPA), Sir William Stewart, has said that "evidence of potentially harmful effects of microwave radiation had become more persuasive over the past five years." His report said that while there was a lack of hard information of damage to health, the approach should be precautionary.[1] The HPA, however, disagrees with his assessment, and claims that there is no risk and no need for precaution. The official stance of the Health Protection Agency is that there is currently no proven risk from RF communication devices.




Health effects of electric power transmission


The preponderance of evidence suggests that the low-power, low-frequency, electromagnetic radiation associated with household current does not constitute a short or long term health hazard, and whilst some biophysical mechanisms for the promotion of cancer have been proposed (such as the electric fields around powerlines attracting aerosol pollutants.[10][11]), none have been substantiated.[12][13][14][15][16][17] Nevertheless, some research has implicated exposure in a number of adverse health effects. These include, but are not limited to, childhood leukemia (references below), adult leukemia[18], neurodegenerative diseases (such as amyotrophic lateral sclerosis)[19][20][21], miscarriage[22][23][24], and clinical depression.


[edit] Leukemia and cancer
In 1996, the Stevens Report was released by the National Academy of Sciences. Based on the current research of EMF produced from power lines, the report concluded that there was no evidence that showed exposure to EMF from power lines presented a human health hazard. Another report was released on July 3, 1997 by the National Cancer Institute (NCI). The report published in the New England Journal of Medicine, "Residential Exposure to Magnetic Fields and Acute Lymphoblastic Leukemia in Children" [25] was a result of a seven year epidemiological investigation. The study investigated 638 children with acute lymphoblastic leukemia (ALL) and 620 controls and concluded that their study

provides little evidence that living in homes characterized by high measured time-weighted average magnetic-field levels or by the highest wire-code category increases the risk of ALL in children.

The NCI study was corroborated by a 1999 Canadian epidemiological study of leukemia in children. As a result of the NCI's findings, the US Department of Energy disbanded the EMF Research and Public Information Dissemination (RAPID) Program citing that its services were no longer needed.


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#9 wvbig

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Posted 9 April 2009 - 05:14 PM

Where are electromagnetic fields usually found? I mean around what natural features? Streams, rocks, etc...
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#10 insane_alien

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Posted 9 April 2009 - 06:01 PM

Where are electromagnetic fields usually found?


everywhere. particularly during the day.
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