16 IowaDoug:

Don’t be in a panic about EMP. Unless there is something I don’t know, it is a non issue. It is true that the Starfish experiment temporarily knocked out the power in Hawaii. (Starfish was a very high altitude nuclear explosion. The physics involved a very rapid expansion of a plasma ball which brushed aside the Earth’s magnetic field.) However, by far most of the energy of interest was in the form of long wavelength electromagnetic waves. These long waves coupled into the very long power lines which acted as very long wavelength antennas. The coupled pulse temporarily knocked out some of the electric grid’s infrastructure.

I don’t recall that damage was done to any other electrical apparatus, including the few transistor radios that were then available. In order to create damage to modern electronics it will be necessary to generate a truly stupendous electric field. My guess is that ordinary surge protecting power strips will provide adequate protection.

If you are really worried, you might do a couple of things: 1) invest in a backup gas powered generator; 2) get some backup electronics and put them in a metal box.

However, missile carried nuclear weapons are enormously expensive (hundreds of millions of dollars). Anyone who has them also has competent physicists who can calculate Poynting Vectors. I believe it is very unlikely that such folks would waste a such a valuable resource on the odd chance of blowing out part of our electronic infrastructure – particularly since making big bangs near the ground would be much more effective.

Finally, I note that the internet was designed specifically (by DARPA) to survive all types of nuclear attack.

P.S. I was given this very problem as the final exam (it was the whole take-home exam) in my Graduate School Electricity & Magnetism course.