"Armstrongs"? Either this is a misspelling of Angstroms (a unit of length, 10^-10 meters), or it's a unit I've never heard of. And in general, radio waves are larger (longer wavelength, lower frequency, lower energy) than microwaves.
Holes in my knowledge.
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"Armstrongs"? Either this is a misspelling of Angstroms (a unit of length, 10^-10 meters), or it's a unit I've never heard of. And in general, radio waves are larger (longer wavelength, lower frequency, lower energy) than microwaves.
rwguinn
Penultimate Amazing
um... No.
See the "Mythbusters" episode where they discovered that meat in a u-wave oven actually cooks from the outside-in.
you can test it yourself--but a roast in the oven, cook for 5 minutes. outside will be well-done, inside will be rare.
rwguinn
Penultimate Amazing
Radio waves are Electromagnetic spectrum emmisions. Microwaves are Electromagnetic spectrum emmisions. The only difference is in the frequency-and thus the energy contained. Higher frequency=higher energy content. They are the same thing otherwise.
and the word is Angstrom
Edited to add--11m (26Mhz) wavelength is pretty much cosmic background--the "radio waves" output by stars and all other sources of radio in the universe.
and how do you think Radio telescopes work? lots of frequencies outh there-all natural Don't go homeopathic on us, here....
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CurtC
Illuminator
Assuming you mean Angstroms, this is generally right, but there's not a sharp dividing line between what's called "microwave" and what's called "RF". Even using this sharp classification, the radiation from microwave ovens would be radio waves, not microwaves, because their wavelength is longer than 10 cm.
Yes, I know what AM means, but I was using it as shorthand to designate frequencies used for transmission of AM radio, which is around 1 MHz.
I don't mean to be nitpicking here, but disagreeing with your general point. Things that are viewed as potentially harmful include UV rays, gamma rays, cosmic rays, x-rays, and to a lesser extent microwaves. Only x-rays and microwaves are artificially generated. Generally safe frequencies are those used for AM radio, FM radio, low-band cell phones, etc., and we are exposed to those pretty much exclusively from artificial sources. I think it would be true to say that in general, most artificial EM sources are harmless, most natural ones are potentially harmful.
Actually, there is a good chance you would be blinded before you were otherwise made uncomfortable. Your retina is especially easy to damage by microwave radiation.
Assuming that your retinas aren't in the 'line of fire', your premise would only be true if the intensity of the microwaves were sufficiently low. There are plenty of microwave sources that would be pretty much instant death if they were to hit you in the torso. If it was an extremity hit, you could just count on losing it. (If you didn't just lose it on the spot)
For instance, the (now retired) TPS-32 air search radar transmitted 2.3 million watts. That is an incredibly hazardous amount of power. Newer radars tend to have lower transmitter power as the receivers have gotten more sensitive over the years. I suspect that if you looked into it, you could find current or past 'early warning' (along the Alaskan coast?) radars that are in the 10's of millions of watts.
The main radar that I worked on while I was in the Marines was the TPS-63/65. It was a short range radar. It 'only' put out 100k watts. I've had two pretty scary moments, even with that 'puny' radar.
Bronze Dog
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Pardon me if I'm stepping out of my bounds, but doesn't breathing air over 140 degrees F cause 1d6 points of fire damage per round?
Reviewing some of the mis-statements in this thread.....
Microwaves are radio waves. They are at the high end of the spectrum to be sure, but still radio waves. For instance, all the radars I have worked on are in the 1 - 1.5 GHz range. Your cordless phone in your house is probably opperating at 2.4 GHz or even 5.8GHz (well into the microwave spectrum), is this not radio? I was tech on a 'data' radio that broadcast at better than 10GHz.
And here is link to Federal Long-Range Spectrum Plan for the 10 to 100 GHz Radio Frequency Spectrum
http://www.ntia.doc.gov/osmhome/LRSP/LRSP5c.htm
Also, AM in the traditional +/- 1MHz range can be quite lethal. It depends on the power. Go grab the antenna of high power transmitter and you will find it to be quite deadly.
And almost everything in the following is wrong....
While it is true that you have to be into UV or higher frequency range for the EM radiation to be considered to be ionizing, (which just means that a single photon of it can cause molecular re-arrangement), that doesn't mean that lower freqencies are necessarily 'safe'. It just means that lower freqencies cause their harm when the power levels are so high that it can not be dissipated by whatever is absorbing them (so, the damage is done thermally rather than through ionization).
1) X-rays and Microwaves are both created in abundance by nature.
2) And the bands used by AM, FM and cell phone are made in abundance by nature as well.
3) It is not safe to say that most articial EM sources are harmless and most natural ones are harmful. Both natural and artificial EM source can and do run the spectrum from harmless to lethal.
Microwaves are radio waves. They are at the high end of the spectrum to be sure, but still radio waves. For instance, all the radars I have worked on are in the 1 - 1.5 GHz range. Your cordless phone in your house is probably opperating at 2.4 GHz or even 5.8GHz (well into the microwave spectrum), is this not radio? I was tech on a 'data' radio that broadcast at better than 10GHz.
And here is link to Federal Long-Range Spectrum Plan for the 10 to 100 GHz Radio Frequency Spectrum
http://www.ntia.doc.gov/osmhome/LRSP/LRSP5c.htm
Also, AM in the traditional +/- 1MHz range can be quite lethal. It depends on the power. Go grab the antenna of high power transmitter and you will find it to be quite deadly.
And almost everything in the following is wrong....
While it is true that you have to be into UV or higher frequency range for the EM radiation to be considered to be ionizing, (which just means that a single photon of it can cause molecular re-arrangement), that doesn't mean that lower freqencies are necessarily 'safe'. It just means that lower freqencies cause their harm when the power levels are so high that it can not be dissipated by whatever is absorbing them (so, the damage is done thermally rather than through ionization).
1) X-rays and Microwaves are both created in abundance by nature.
2) And the bands used by AM, FM and cell phone are made in abundance by nature as well.
3) It is not safe to say that most articial EM sources are harmless and most natural ones are harmful. Both natural and artificial EM source can and do run the spectrum from harmless to lethal.
rwguinn
Penultimate Amazing
He he, I love these pedantic arguments. I'm an optical/infrared observational astronomer, and as far as I'm concerned if the wavelength is too long to use an optical telescope then it's a radio wave.
Picker of nits!
RationalVetMed
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An Armstrong is the precise length of a small step for man, roughly 1/6 billionth of a giant leap.
Yuri
I should have done this post first, rather than last.....
to the OP.
By the preponderance evidence that we (humans) have gathered to date....
1) Magnetic fields are harmless at the strengths that a person is likely to ever encounter.
2) RF radiation is generally harmless, provided that the power level is reasonably low (A clue that you are in especially high RF beam might be that your fluorescent lights are lit up, but the switch is 'off')
3) Ionizing radiation is generally harmful, and the damage is cumulative.
3a) Except that we need some amount of UV exposure to produce Vitamin D
3b) And our bodies are surprisingly good at repairing the damage of ionizing radiation if it doesn't accumulate too quickly.
to the OP.
By the preponderance evidence that we (humans) have gathered to date....
1) Magnetic fields are harmless at the strengths that a person is likely to ever encounter.
2) RF radiation is generally harmless, provided that the power level is reasonably low (A clue that you are in especially high RF beam might be that your fluorescent lights are lit up, but the switch is 'off')
3) Ionizing radiation is generally harmful, and the damage is cumulative.
3a) Except that we need some amount of UV exposure to produce Vitamin D
3b) And our bodies are surprisingly good at repairing the damage of ionizing radiation if it doesn't accumulate too quickly.
roger
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Just think of them as the same thing, just at different energy levels. As the frequency goes up, so does the energy. So, for example, microwaves are at a higher frequency, and hence higher energy, than radio waves. Visible light is higher yet, and UV higher yet. Go stand in the sun for long enough and you'll be burned. xrays are so energetic they go through your body. Gamma rays are even more energetic, and they can alter DNA, causing cancer. This is why people tend to scoff about things like cell phones causing health issues. The amount of energy is so low there is no known mechanism by which the relatively low energy could cause any damage to the body.
Here's a nice chart:
http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html
SquishyDave
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That's the easy bit roger, I've always understood that. What wollery said quite a bit of the way up though rings a bell.
So if I am understanding correctly, a magnetic field is just EM radiation with a frequency of 0, this according the formulas gives it an infinite wavelength, and so it is static (it's, not and can't be, flying through space). It seems to me this would also make it pretty low energy, which explains why you can expose a frog to so much of it and leave it completely unharmed.
And what propogates EM through a vacuum is that it is a magnetic field bouncing off an electric field which bounces of the magnetic field which bounces of the eletric field and so on. How fast they do this determines the type of type of EM radiation. Overly simplistic perhaps but I think I do remember seeing something about this on TV at some point. Have I misunderstood?
Marker
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Yes of course they are all the same thing. Light also falls into this category. All EM waves are, well, EM waves. You might as well say Light is the same as Radio and that UV is the same as IR. The terms Microwave, Infra Red, Radio etc are there precisley to identify the frequency range in question.
Gee a typo - fifty lashes.
|f you were before me I would slap you across the face with my gloves for that (if I had any gloves).
Lets put this into context here. SquishyDave was talking about scanning the place where he worked.
Granted there are lots of dangerous forms of naturally occuring electromagnetic radiation out there but if there is anything dangerous in his working environment it is more likely to be produced by something artificial like an unshielded microwave oven, X-ray machine, or other piece of electronic or electrical apparatus. If he is inside, then naturally occuring UV is unlikely to be a problem. If his workplace is on the surface of the earth and protected by an atmosphere then most of the other naturally occuring dangerous forms of EM are unlikely to be a problem.
Oh and yes, if you are a radio astronomer/astrophysicist then it is reasonable to regard all EM other than light as radio waves. But I dont think Squishy Dave is. Nor is the guy at my local electrical store so thats why I wont be asking him for a "Radio Oven"
Finally, regarding the cooking of internal organs. I believe unshielded microwaves can cause considerable cellular damage to internal organs before the owner of those organs becomes aware of any pain. Although I can no longer rememeber the source, it is not my habit to accept urban myths uncritically. Nevertheless, I may be wrong on this - perhaps we could start a new thread.
Oh and dont talk to me about radio astronomers. They built Jodrell Bank on top of our house.
Ziggurat
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Actually, it would take a much higher field IN ADDITION to a larger area in order to make a person float. The reason is that the linear force created by a magnetic field (as opposed to the torque it can apply to a magnet) is NOT proportional to the field itself, but instead is proportional to the gradient of the field (how fast the field is changing). So you'd need a field that was changing just as fast as the field used to levitate a frog, but that same change would have to continue over a much larger area. So that requires a much higher field (as in more than a factor of 10, since the linear dimensions required are more than 10x as big for a person) in addition to the larger volume it's applied over, and that's well beyond our engineering capabilities at the moment. Far enough in the future, who knows?
a_unique_person
Director of Hatcheries and Conditioning
So how does a magnetic field act on an organic object that is not made up of what I would normally expect a magnetic field to act on?
Silly Green Monkey
Cowardly Lurking in the Shadows of Greatness
Vertebrates use hemoglobin to transport oxygen in the blood, which binds oxygen to an iron molecule held in the protein. The magnetic field would work on the iron in the blood and stored in the marrow.
Ziggurat
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Moving electrons in a magnetic field feel a force perpendicular to their direction of motion. For an electron orbiting around an atom, if this force is in the same direction as the electrostatic attraction of the nuclei, then the radius of the orbit will compress. If the force is opposite the attraction of the nuclei, the orbit will expand. This creates a difference in the magnetic moment from electron orbits going clockwise vs. counterclockwise with respect to the applied magnetic field (without the field, the orbital moments should cancel). This creates a small diamagnetic susceptibility (meaning it aquires a magnetic polarization opposing an applied field) for ALL atoms, not just what we normally consider to be magnetic atoms. Diamagnets feel a repulsive force from areas of higher magnetic field, which is how the levitation effect is created.
This diamagnetic susceptibility is small compared to what you get in typical magnetic materials (which is why it gets ignored if there is any paramagnetic susceptibility). In typical magnetic materials, the change in magnetic moment comes from reorienting the spin moment of electrons themselves, not from changes in their orbital moments. With paramagnetism or ferromagnetism (where the polarization is parallel to the field, not anti-parallel), the material is always attracted to areas of higher magnetic field. Since the force is attractive, it is not possible to create a stable levitation scenario with a paramagnet without active feedback to control the field, since the closer the material gets to the high-field region, the harder it gets attracted, so any perturbations will make the object either stick to the magnet itself or fall away.
SquishyDave
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Try saying that 3 times fast.