Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Explosively Pumped Flux Compression Generator detonated a mile away or so, what damage would be done to my phone, and other electronics? I would imagine it would be similar to a CD in the microwave where every trace would act as an antenna and then a fuse? Or am I thinking about a much stronger nuclear EMP?

I have read about Starfish Prime, but that was in 1962 and we didn't have the microelectronics that we do now, basically anything with transistors would be fried or what?

share|cite|improve this question

migrated from Mar 8 '13 at 5:14

This question came from our site for electronics and electrical engineering professionals, students, and enthusiasts.

Surprised nobody has had a shot at answering this yet! It seems pretty difficult to find reliable information regarding EMPs and the devices create them - perhaps this isn't entirely surprising. Anyway, here is by very back-of-the-envelope attempt at answering your question. Hopefully it'll be right to within a couple of orders of magnitude!

So starting off with a power of 10TW, the total power arriving at your phone will be:

$P_{\rm phone} = Intensity \times Area_{\rm phone}$

Using an intitial power of 10TW (from Wiki), a distance of 1 mile and an area of 10cm$^2$, this gives us a power of around 5MW arriving at your phone.

Now the frequencies of that 5MW will be spread over a very large range ("from DC to daylight - again from Wiki") or in other words from 0 to 10$^{13}$Hz. Ish.

Your phone's circuitry will only effectively couple to a relatively narrow range of frequencies of that mix. (Note here that we're also implicitly assuming the distribution of the power spectrally to be white - the same at all frequencies). Let's wave a finger in the air and plump for 100MHz coupling bandwidth - this now means that your phone is only "absorbing" $1 \times 10^{-5}$ of the incident power, or 50W.

Given the big assumptions I've made regarding the coupling bandwidth, I think it's safe to also assume that 100% of this 50W of incident EM radiation is converted into electrical currents.

It might not seem like much, but mobile phones have tiny wires that aren't built large currents and typically will only draw 1 or 2W.

So, in conclusion - with a vast amount of handwaving - it's conceivable that your phone would survive the blast, but, in my opinion, not terribly likely. I guess it would depend on the orientation of your phone to some extent. Perhaps someone else can help pin down my assumptions a little further?

share|cite|improve this answer
A couple of extra thoughts that I didn't consider in the above - the duration of the pulse may also be important in terms of the total energy delivered, and the phone's circuitry will probably couple effectively to the pulse at a number of different frequencies (i.e. more energy absorbed meaning more likely to damage the phone). – Ned Yoxall Dec 20 '13 at 10:59
You slipped a few decimal points somewhere. The surface area of a sphere with radius 1 mile is 32.6M square meters. The 10 TW spread over that surface is 307 kW per square meter. 10 square cm is 1/1000 of a square meter, so would intercept about 300 W. However, power is not so useful for a short pulse. Total energy would be a better metric. Even if the pulse is 10 us long, the phone would only get 3 mJ. – Olin Lathrop Mar 20 '14 at 13:53

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.