REM and Electron Volts are two completely different critters. EV is a measure of electrical energy not radiation such as gamma. Rem is radiation Equivalant Man. It is a conversion unit that measures the amount of damage to the human body which is different from electrical damage. There are several different types of radiation you can be exposed to.

Unless you are attached to a very large conductor EMP will not hurt you. Ionnizing radiation on the othere hand is when radiation passes through the body causing damage to the cells. LD 50/50 or the leathal dose where half the people exposed to it will die. Depending upon which study you read LD 50/50 is between 500 to 600 REM.

As soon as the magnatron powers up, the CD is stuffed. Wheres my reference? My kitchen and some of my friends kitchens. Ive put cd's that dont look damaged back into drives to try and read them. Feel free to come around and test. You dont need the 8 seconds. The 8 seconds was to let people know that it might get a little dangerous and that they look pretty cool after a few seconds.
The microwave is a high frequency eletro magnetic wave, an EMP is a electr magnetic pulse. Both will induce electical currents and not just in a wire conductor. In what way do you not think that a cd will not have any induced currents.

As to how much damage a device will make depends on its design, size, location etc and how many of them there are.
As to the likely chance of this happening, I think I will be pretty safe where I am.
I am more worried about lighning around here, as this is a much greater risk. Protecting for lightning will provide some protection from a non nuclear EMP if the device doesnt go off close.

Some of the damage Ive seen caused by lightning has been a 1 inch bolt holding a plate on a wall blow itself apart and embed itself in a limestone wall on the other side of the room.
Ive also seen a builbing take a hit through an antenna on the roof which looked like an afro. Every computer in the 3 story building had its BIOS ROM chips wiped, even the ones not switched on.

Actually, the fundamental measurement of radiation is the electron volt. Gamma rays are measured in eV, although the higher the eV is, the shorter the wavelength and the higher the frequency. As the frequency increases, the energy increases. The threshold where the frequency becomes ionizing occurs at the UV range, ie it has the ability to strip electrons from atoms, about 10 eV, or 2,500 Terra Hertz (120 nanometer wavelength). This, you will note is independent of the amplitude of the wave. Since an emp is a function of both amplitude and frequency, a nuke emp has a lot of high extremely high frequency components, which means they can contain a lot of x-ray and gamma ray energy. I believe there is a formula for converting eV to RAD (Radiation Absorbed Dose), which can then be converted to REM (Rad Equivalent Man), which takes into consideration the type of exposure. It's been a few years since the college Rad Health Physics class I took, so I don't know the specific formulas anymore, but they are out there (I think it is 1 Rad =6.24E7 MeV, or 62.4 trillion electron volts). There is a table that shows what damage occurs to the human body at different REM doses. I believe the first to go are the crypt cells of the small intestine at something like 50 REM, then the marrow, and so on. Lethal doses aren't immediately lethal, so a 300 to 500 REM dose takes time to kill, whereas a 5,000 REM dose is going to shut you down before you can take a couple steps. Here's a link to an industry standard exposure table, which has the LD 50/50 actually slightly lower than you noted:

http://www.pimahealth.org/dmat/dmat_radiationchart.pdf

Basically, if you are close enough to hear the bright blue arcs going between the two PU spheres, you are toast before you can get out of the room.

The statement that you have to be attached to a very large conductor to be effected by an EMP is limited to the size of the field you are exposed to. If the field you are exposed to is intense enough, you don't need to be attached to anything and you will be cooked.

Here's another aspect to consider about popping a conventional EMP (forget the nuke aspects for a moment, let's just use non-ionizing fields). EMPs generate high momentary electromagnetic/electrostatic fields. Having induced emf fields using large coils, I can tell you that if the field is high enough, it can have nasty effects on the musculo-skeletal system. We had a coil that we put tools in to magnetize by pulsing the coil with a high voltage transient. We experimented with animals using this field and found out that the pulse at a close proximity fairly turned the critter (which was not electrically connected to the coil in any way) inside out!!! Now, while it's not likely that people will be that close to the source, it is important to note that the field we were creating was not nearly as big as the tactical EMPs we've been talking about here. Even at that, the coil blew an electrically isolated DMM up from over three feet away.

Another experiment used a cascading voltage multiplier to bump line voltage up to about 115kv. We called it the symphony box, because it made beautiful arcing noises if you moved the probe near any equipment that the return was clipped to. We clipped the return on a piece of equipment and without even arcing the probe we could just wave the tip around inside the chassis and all the semiconductors would blow. It was a good way of decommissioning some piece of junk that an owner wanted us to resurrect for more than the thing was worth. Some people just can't be convinced otherwise.

Nuke EMPs do contain an ionizing component, which has to be considered as part of the whole effect. Propagational loss due to high altitude detonation is likely going to keep them from generating a significant instantaneous dose, but it is still there. Likewise, propagational loss keeps the amplitude component from generating an acute biologic effect as well.

The bottom line is REM and eV are not two completely different critters. If it were, then there would be no such thing as ionizing rays, like UV, X-Ray and Gamma. EMPs do pose a health risk if the relative intensity of the exposure is high enough, regardless of the grounding potential of the individual exposed.

There's an awful lot of this sort of information on the internet, so I won't go any deeper (heck, I've probably walked off the deep end already). Do some more research if you really want to know, but I classify such information as "nice to know" trivia. <img src="/images/graemlins/grin.gif" alt="" />

Just an observation. I think it's been rather confusing (it has for me) that people have been talking about different kinds of EMP in this thread and it seems to be generating some frustration for some readers. For me, the word "EMP" means EMP from a high altitude nuclear detonation and that's the paradigm I was reading from. I think most of us are at least vaguely familiar with the characteristics of such a phenomenon from Cold War "common knowledge", such as massive damage to electrical systems but no damage to people. That's why benjammin's comment about EMP being harmful to people was perplexing to me at first.

But then as posters elaborated some more and I did some Googling, it's evident that some are referring to other kinds of EMP, like from High Power Microwave devices that can use batteries or explosives to generate their energy (a "suitcase EMP"). And some people are referring to intense EM fields created in the lab under controlled conditions. For example, a field that lasts long enough to wave a probe two inches from equipment to destroy it is different than the 10 nanosecond EMP of a high altitude detonation 250 miles up and 1,000 miles away. Yes, all of them are intense EM fields, but we're talking about pretty different phenomenon in terms of frequency, intensity, duration, exposure, range, how they're generated, etc.

Anyway, in case there are other people who know just enough physics to be confused like I was, I think much of the confusion is because we're talking apples and oranges in some cases. It's like having a discussion on the dangers of and defense against "biological weapons" and one person is thinking of the characteristics of anthrax spores and the other person is thinking of small pox virus.

Actually, there's not as much difference as you might think between all of the above.

What kills the solid state circuits really is the voltage. Whether the duration of exposure is 10 nanoseconds or 10 seconds won't make much difference. I relate the probe story because it was the voltage that killed the transistors, and not how long I held the probe in the case. BTW, the duration of the EMP for a nuclear detonation is quite a bit longer than 10 nanoseconds. That's more like the duration of the spike from a lightning strike. But like I say, it isn't the duration, but the intensity.

In the remake of Ocean's Eleven (with George Clooney), they demonstrated the use of a "pinch", which was a chemically induced emp generator. While the characteristics were a bit embellished, the idea was about right (I'd wanted to avoid that reference, but I guess it is the only good one I can cite for the layman).

My point was precisely that not all EMPs are created equal, or have the same characteristics, though they share many attributes, the most noteworthy of which is the high intensity transitory electromagnetic field. You really could put all other arguments aside and just state that the purpose of EMPs is to blow solid state electronics all to heck.

This isn't an apples and oranges comparison, more like a Macintosh to Golden Delicious to Granny Smith type comparison. We are not nearly so divurgent here as the biologic references you refer to.

I guess the bottom line here is, "If the lights go out and your watch quits, you got greater concerns than checking your Ipod, and I hope you brought a good pair of walking shoes with you. <img src="/images/graemlins/smirk.gif" alt="" />

quote You really could put all other arguments aside and just state that the purpose of EMPs is to blow solid state electronics all to heck.
I guess the bottom line here is, "If the lights go out and your watch quits, you got greater concerns than checking your Ipod, and I hope you brought a good pair of walking shoes with you. unquote

I agree with Ben, that pretty much sums it up, I too was going from the high altitude nuke airburst perspective, which is a very real threat and has been for some time from a variety of enemies, just now it is more likely with terrorists rather than a country like Russia or China. The technology is now available to just about anybody with enough money to buy or build a nuke and a delivery system such as a SCUD missle.

Ok. So great. Everything I own is going to be screwed. How far away do I have to send my backup DVDs? With an "Oceans 11" type or an airburst? Are we talking miles or hundreds of miles or cross continents?

Ben you are still mixing apples and oranges. I speak from a considerable amount of experiance. 9 years in the navy nuclear power program 2 of which were as an instructor.

Yes there are components of radiation involved if the pulse is generated by a nuclear explosion. But it is not the Electro MAGNETIC pulse. And it is a moving magnetic field that generates the damage in electrical equipment. By creating a voltage spike in the wiring. And that is generally of very short duration.

If you are exposed to high levels of radiation along with a pulse it is the radiation that fries you.

A strong enough magnetic field can effect the body directly. That is because hemoglobin in the blood contains iron.It can literally pull that iron or your blood out of you. The level though is tremendously high. That is why you are not allowed near cyclotrons while in operation. To get that kind of magnetic level even from a nuclear blast. Well let's just say the field might affect the floating ash of your body because you are at ground zero. Well inside the fireball.

Actually, it is the burst of high energy gamma rays from the nuclear blast that induces the EMP, by what's called Compton Scattering. Relative to our perception, the duration of the EMP generation cycle is quite short (typically 10 milliseconds or so), on a timescale calibrated to such events, 10 milliseconds is way longer than 10 nanoseconds (kinda like comparing minutes to eons on our timescale).

Radiation hardening is a legitimate concern. Radiation can cause as much or more damage than the EMP. TTL was not as susceptible to radiation induced transient failure, but the current commercial technology is based more on MOS semiconductors, which are susceptible to ionizing radiation at levels below 1 RAD, which is a possible exposure level in an airburst at 20-40 km, which happens to be where nuke EMPs are targeted to detonate because that's where the Gamma radiation induces the highest EMP level in the atmosphere. Of course, all this information is published on the internet. Typically with EMPs, the solid state device blows at the semiconductor junction because the Peak Inverse Voltage is exceeded. An EMP creates a voltage spike in all the conductors, including the lans of the circuit boards, the compnent leads, the internal substrates, and the external circuit wiring as you noted. Of course, you can electrically shield these circuits against the EMP, but that shield may not prevent the radiation exposure, especially if it is mostly Gamma, and the circuit will blow anyways. Given that most electronic circuits still employ lead based solder, high energy nuetrons (also present in nuke emp detonations) which also are difficult to shield against can induce a secondary x-ray emission due to the Bremstralung effect, at a fairly close proximity to the semiconductor junction I might add, which said junctions are also susceptible to (x-rays ionize substrate atoms liberating electrons, which induce an emf at the junction, and also a photonic emission that deteriorates the junction). These are all factors that have to be sheided against when putting electronic equipment in space as well, very real concerns that have little to do with shielding against EMPs. There's a good deal of technology devoted to it, so it must be a design factor for a reason.

I'll agree that the radiation surge from a nuke EMP will get you long before the strength of the electromagnetic field does. I'm not sure what your counterpoint was in that statement.

I would add that an electromagnetic field does more than just act on the hemoglobin. High transient spike EMPs induce a temporary field in the skeletal structure. This transient has the effect of rippling the bones as eddy fields develop, and the result is signficant fracture of the structure. As before, I would agree that the radiation will get you before the electromagnetic field does in a Nuke EMP, but in a conventional EMP, lacking the radiation component, it is advisable that you keep your distance from the point of origin. Let's put it this way, I wouldn't want to be holding on to a suitcase containing a non-nuke emp when the thing went off, unless I want to know real, unequivocal pain. Our experiments indicated that significant bone fracture occurred using transient fields that were lower than what was needed to rupture or extract hemoglobin. Independent variables made it hard to predict or determine what gaussian level was needed, but it was distinctly lower.

I think it is still apples and apples.

As I also discovered after my Naval tour in the Cryptologic program, they don't teach you everything there. <img src="/images/graemlins/grin.gif" alt="" />

So, uh, you basically have more important things to worry about than your iPOD!

Can you burying electronic devices and have them unaffected by an EMP?