Nuclear blasts and electrical disruptions

The way I remember it from the movie “The Day After”, the electromagnetic radiation from the bomb disabled electrical devices even a great distance away from the blast. This included things like cars and transistor radios.

I think I understand how microwaves can melt computer memories (because the circuitry is to tiny, shaking the molecules even slightly will basically melt the whole thing). But would this really happen to other devices as well?

Nuclear blasts produce enormous amounts of gamma radiation in a very short burst. Gamma radiation is classified as “ionizing radiation”, because when it strikes an atom, it flings electrons off of that atom. In a nuclear burst, in a fraction of a second an enormous number of electrons are flung around. As a result, very strong electric and magnetic fields are created. These fields will induce electric currents in any conductive material they find. Electronic devices are simply vulnerable to the fact that a current far too strong for them to handle may be induced in their circuits.

Microwaves are not a big problem for electronic devices. The waves that kill electronics are much lower in frequency.

Have you ever heard a nearby radio station being faintly received on stereo speakers, even though the stereo was turned off? The strong broadcasted signal is inducing a voltage in the speaker wire, as if it were an antenna. That voltage is not amplified by the stereo’s electronics, but it’s still enough to move the speaker cone and produce faint sound.

Immediately after a nuke strike, there’s so much energy flying around that it can induce a voltage in almost any wire, even the small ones inside a computer. When every circuit in a device receives a voltage spike at the same time, a lot of important stuff is liable to burn out. (Imagine what would happen to your speakers if the radio station suddenly broadcast a burst of static at 1,000,000 times its normal power.)

Of course I don’t fit in; I’m part of a better puzzle.

Actually, I did once hear a local FM station coming from my kitchen telephone! Until then, I did not believe people who claimed that their dental fillings picked up radio stations, but now I do.

Thanks for the explanation. It makes sense. I guess the reason why our electrical brains would continue to function is the comparative lack of metal?

I would guess that yes, the fact that the brain is not as conductive as metal would help. Also, most electronic devices contain induction coils, which would dramatically increase their vulnerability. I would expect that there would be a point at which the EMP could effect the brain, probably causing a grand mal seizure. Since I’ve never heard of this, perhaps that threshold is close enough to the blast to instantly kill/vaporize.

I’ll agree with Undead Dude once again. There must be a radius in which the EMP is strong enough to screw up nerve impulses, but I’d say that the “kill zone” of the blast and radiation is much larger.

Note that EMP in general does not come only from a nuclear blast; some amount is emmitted from every electrical device. The difference is one of degree, because nukes dump out so damn much energy at once.
There are (unfounded, AFAIK) rumors that the US military is attempting to develop EMP as a weapon. If you had a powerful EMP-gun of some kind, you could theoretically incapacitate enemy soldiers and wreck lots of their equipment, without having to actually kill anyone. (But note again that I’ve heard these as rumors, in the same breath as stories about UFOs at Area 51.)

Of course I don’t fit in; I’m part of a better puzzle.

to what Aura said:

I seem to recall this report on 60 Minutes or 20/20, or one of those news magazine shows… Anyway, it dealt with “New Terrorists”. Their main point was this guy who was ably to make these machines, abotu the size of a suitcase, which emitted I believe microwaves, which were powerful enough to screw up electronics from quite a distance. Not exactly an EMP gun, but the same application

Poverty P’uh

Cecil has a column related to EMP. It suggests some of the devices vulnerable to EMP.

Now just a minute there fellers. Doesn’t the circuitry in a radio translate the RF broadcast into audio frequencies? And then amplify it, so we can hear Ole Donnovan singing about saffron?

Work like you don’t need the money…
Love like you’ve never been hurt…
Dance like nobody’s watching! …(Paraphrased)

Well, there are two frequencies in a radio broadcast. There is the frequency of the carrier wave, and then there is the frequency of the sound encoded within it. So for example, with an AM broadcast, if someone struck a standard concert “A” tuning fork, the amplitude of the carrier wave would rise and fall 440 times per second.

So the real sound frequency is in there. It doesn’t need to be translated so to speak. It just needs to be extracted.