Science in Fiction – EMP (Electromagnetic Pulse)

science in fictionI’m going to largely skip over how to generate an electomagnetic pulse.  Primarily, a nuclear bomb is to blame.  The military might be working on other means, but I sure as hell don’t know about it.

 

Affects on Electronics

I’ve seen movies and TV shows where EMPs were used, and frequently, they like to use it as a plot device to temporarily disable the electronics in an area.  Ocean’s 11 knocked out an area of Las Vegas for 30 seconds.  Leverage had an EMP gun that could take out electronics for 30 minutes.

But here’s the problem with that — an EMP fries electronics.  They are permanently damaged by the pulse.  Older electronics might be able to survive, but modern electronics cannot without protection.  As we’ve become more advanced, circuits have become smaller and more fragile, less capable of handling the rapidly alternating currents of an EMP.  It’s why lightning is so deadly to our gadgets.

To understand what an EMP does, imagine an epileptic looking at a strobe light.  The light flashes, spazzing out the person’s brain and causing it to misfire rapidly.  With an EMP, the pulse triggers an electrical charge to alternate through a circuit.  This charge alternates so fast that the circuit burns out.   Permanent damage.

Protection

Electronics can be protected primarily using Faraday Cages.  See Wikipedia for more details.  Pretty much all forms of protection involve some form of Faraday Cage, which disrupts the alternating wavelengths that cause the damage to circuitry.  On the cheap, a Faraday Cage can be created with a cardboard box and a bunch of aluminum foil.  See instructions here.

Creating an EMP

Primarily, EMPs in the way we think of them are caused by nuclear bombs, and that’s about it.  There are many types of EMPs coming from a wide variety of sources, like lightning and electrostatic discharge, but these don’t create the more widespread effects an author might be looking for.

There are two types of EMPs caused by nuclear bombs: NEMP (nuclear EMP) and HEMP (high altitude EMP).  The primary difference between the two is location of detonation.  NEMPs are detonated on the ground, while HEMPs are detonated hundreds of kilometers above the Earth’s surface.  Basically, an HEMP would be what was used in the events in the TV show Dark Angel.  In fact, to my knowledge, that show is one of the most accurate depictions of the results of an EMP I’ve been able to find.  The only thing I’ve ever questioned about the events in that show were the government’s lack of reaction to the incident, or preparedness for that matter.

2 Comments so far:

  1. Ruth Fanshaw says:

    Thanks, this is very helpful. 🙂 Have bookmarked this for future reference. 🙂

    Could you please clarify a couple of points for me?

    Does a Faraday Cage cause the EMP to have no effect whatsoever, or does it merely lessen the effects? And how old would the electronics need to be in order to survive?

    Thanks. 🙂

    • Hello, and thanks for the questions (and sorry for the delay). A properly designed Faraday Cage completely negates the effects of the EMP by preventing the waves that cause the damage from passing through. It can’t be partially effective and still provide any effectiveness at all. Fried is fried.

      As for age, it depends on the technology. If it has a circuitboard, you can pretty much guarantee it’ll be fried. But what items would or would not have circuitboards depends on the that specific technology. Early computers used vacuum tubes (etc.), which would have been completely safe from EMPs. The tubes often needed replacing, but without compromise to the computer at large. That was up to the 1960s.

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