Originally Posted By: turtlevette
I still maintain if the emp kills your computer, the blast kills you. Its amazing how many nuclear scientists we have here.
That's already been demonstrated to be hogwash. You don't get a large N-EMP in a normal airburst. The altitude is crucial for a high energy pulse, and very low-yield devices can generate extremely powerful N-EMPs, particularly if the casing material is thin enough to not absorb too much of the gamma radiation; the peak will be very high, the duration not so much. Your mention of inverse square doesn't mean a lot when well over 90% of the gamma radiation is absorbed by a thick case at the outset and we're surprised that a 1 megaton device doesn't produce a peak burst even twice as powerful as a 10 kiloton device.
A fission device is much more efficient as a N-EMP device than a fusion device. Additionally, you had better brush up on your Maxwell's equations, not to mention the data. According to Glasstone, in his work from the late 1950s and early 1960s, you'll see significantly different rates of drop off depending upon weapon yield and design, not to mention effects due to differences in local magnetic field. The pulse is generated outside the device, not within it, and not necessarily anywhere near it. As has already been alluded to by Skid, it's not the device itself generating the pulse, it's the interaction of the gamma radiation with Earth's magnetic field.
Much of the data from the pre-test-ban early 1960s testing has been declassified. It's out there if you want to look at it, though there is some redacting still evident. Damaging effects on the electronics of that age were noted hundreds of kilometers away from the detonations.
R2d2: That's not quite the same thing, but the point is well taken. We wouldn't necessarily see every vehicle on the road stop in its tracks and us revert to a Stone Age lifestyle. But, the more sensitive the electronic on the car, the worse a time it's likely to have.
Olas: The effectiveness of a Faraday cage depends upon what wavelength it's designed to protect from, and what wavelengths are actually received. But, you are right. The electronics in a car would fare much better inside the car, as they are now, than, say, if all the stuff were concentrated on the roof for some reason, in such a scenario.