|MadSci Network: Physics|
Hello Peter, You are the first person I have talked to from New Zealand. Welcome to the Mad Scientist network! Shortly after nuclear testing began, it was found that some of the instrumentation used to monitor the tests malfunctioned. Careful examination revealed that the electronic circuits were destroyed, and the hunt for the culprit was begun. It didn't take them long at all to discover that the EMP was doing it. Because the explosion occurs so rapidly, on the order of a few billionths of a second, the gamma radiation in the form of electrons, forms a very intense and concentrated pulse of electromagnetic energy. To answer your question, it doesn't matter if the circuit is active or not. Consider a simple tarnsistor radio. Even if you remove the batteries from it, many internal connections remain. The base of a transistor may have a biasing resistor connecting it to ground, and the emitter, through other resistor/capacitor networks, may also be connected to ground. The same applies to the collector. Elements of a circuit share many common paths, albeit through passive components, but the fact remains that they are complete circuits - even without the battery. Therefore, any voltage induced into the wiring or the components themselves, can and will destroy the circuits. On one of the recent space missions, an expirement was attempted which involved trailing a very long, very thin wire from the orbiting spacecraft. They were trying to see if the Electromotive Force (EMF) induced into the wire by the weak magnetic field of the Earth, could be used to power on-board instrumentation, or at least help charge the batteries. Unfortunately, the tether broke, and the experiment was never completed; but the theory was sound. If a weak magnetic field can produce energy in a long wire, think of what an extremely strong field would do in a short wire, such as wire traces on a computer circuit board, or even the electric power transmission lines coming into your home. It truly boggles the mind! Something you might find interesting: After the EMP was discovered and sicentists and others started thinking about how it could affect worldwide communications, they came upon a plan whereby data, voice or otherwise, could be routed around an area affected by the EMP. Packets of data could be sent thru different routes of the system and, in theory, at least one path would remain unaffected and the data would get through. I think you know what resulted. Yup, the Internet! It was originally a joint University/Military project, and ended up being what it is today. Thanks for the question, and if you need any more info, please contact me directly at: firstname.lastname@example.org. Your not-so-mad scientist, Karl Kolbus
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