Physics/EMP

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Question
Hello,
I would like to ask about electromagnetic pulses and their effects on electronic circuits.

I am a junior in electrical engineering, and I am curious because I do not understand why would EMP affect unplugged electronic circuits. I took basic 3 electronics courses covering the basics of both digital and analog electronics, and introductory EM courses so far, and would like an explanation suited to such level. I mean I tried googling but the *basic* answers I get don't reflect what I learned in my courses, and some answers were too sophisticated for me to understand fully. I mean I am not talking about antenna's or waveguides just operational amplifiers and bjts why would those stop working due to EMP?

Answer
Hello hamad,

You probably studied Faraday's Law in Physics.
http://en.wikipedia.org/wiki/Faraday%27s_law_of_induction
It's about a changing magnetic flux in a coil inducing current into a circuit connected to that coil. The coil would not need to be a plain coil of wire. It could be a looping path in a circuit with resistance in it, semiconductors in it, etc. Such as the feedback path in an analog circuit. Op amps and other semiconductor devices have limits beyond which it can be damaged. I am not claiming that those limits would be exceeded by the average EMP. That's a discussion of the mechanism and potential for such damage.

Here is a list of links that will provide further reading material.
http://en.wikipedia.org/wiki/Electromagnetic_pulse
http://ubuntuforums.org/archive/index.php/t-1546273.html
https://answers.yahoo.com/question/index?qid=20110228193408AAFu2mC
https://answers.yahoo.com/question/index?qid=20100221172617AAz50VF
http://www.futurescience.com/emp/EMP-myths.html
https://answers.yahoo.com/question/index?qid=20130723201641AAIpSA1
http://www.physicsforums.com/showthread.php?t=564260

I hope this helps,
Steve

Physics

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Steve Johnson

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I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.

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I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

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BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University

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