# Question about how electricity works.



## ironpony (Apr 17, 2017)

For my screenplay, there is an electroshock torture device, that is used to interrogate a character.  However when it comes to electricity, do you have to hook up two wires to a person?  Usually in movies, there are two wires hooked up the hostage, so I was wondering if two is needed, when building the machine as a prop and writing it, into the script.  Movies like Taken and Face/Off for example, have two wires hooked up to the person.  So do you need two, or could one do it?  
The villain ends up turning the voltage up to kill the person to keep him from talking after, so do you need two wires for that, or could one do it?


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## Jay Greenstein (Apr 17, 2017)

You need voltage to be applied, and a path back to the source. Without that return it's like birds perching on a high voltage wire. They feel nothing.  Standing barefoot on the earth, of concrete on earth could provide the return, since house current uses the ground as a return. But yes, there must be a way to pass current through the body.

You can poke the person with a taser stick, or shoot taser barbs into them, which has both conductors built into the business end.


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## Cran (Apr 17, 2017)

ironpony said:


> For my screenplay, there is an electroshock torture device, that is used to interrogate a character.  However when it comes to electricity, do you have to hook up two wires to a person? ...


No, but as indicated above, you need to complete the circuit somehow. A known cause of domestic electrocution is contact with a live point whilst in contact with a wet surface which has direct or arc contact (short circuit) with the Earth. An effective torture device using electricity and a single live connection completes the circuit via earth with the victim's feet immersed in water. Another is to complete the circuit via a metal frame and the second (return) live point.




> The villain ends up turning the voltage up to kill the person to keep him from talking after, so do you need two wires for that, or could one do it?


One can do it if arranged as above. The difference between pain and death is the amount of current or amps involved. It is the amperage, not the voltage, which kills.


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## ironpony (Apr 18, 2017)

Okay thanks.  Mainly in the script, a guy is tricked into thinking he is being hooked up to a blood pressure mean, and he has the blood pressure cuff put around his arm.

He then finds out it's an electroshock device.  Would he need two blood pressure cuffs, one on each arm?  Or could he just have one, with one wire going through the pump, that could electrocute him?


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## Cran (Apr 18, 2017)

With what else is the ... patient victim ... in (the more direct the better) contact?


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## Thaumiel (Apr 18, 2017)

ironpony said:


> Okay thanks.  Mainly in the script, a guy is tricked into thinking he is being hooked up to a blood pressure mean, and he has the blood pressure cuff put around his arm.
> 
> He then finds out it's an electroshock device.  Would he need two blood pressure cuffs, one on each arm?  Or could he just have one, with one wire going through the pump, that could electrocute him?



Surely you could fit two wires in the tubing going to a single cuff? It would be arm focused (if the shock is big enough it won't matter where it is though really) but it would work if you didn't have another grounding option available.


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## ironpony (Apr 18, 2017)

Okay thanks.



Cran said:


> With what else is the ... patient victim ... in (the more direct the better) contact?



Sorry, I don't know what you mean by this?


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## Cran (Apr 18, 2017)

Cran said:


> With what else is the ... patient victim ... in (the more direct the better) contact?





ironpony said:


> Sorry, I don't know what you mean by this?



Picture the scene in your mind.

The man who is to be "tested" (tortured and/or killed): is he sitting in a chair? Is the frame of the chair metal? Is he wearing jeans with metal studs? Is he barefoot, or wearing shoes with synthetic rubber soles? Leather soles? Are the shoes wet?

The floor: is it concrete? bare dirt? Wet?

The apparent blood pressure machine: Is it on a metal frame? Is it on a metal-framed table? Could any of that metal be in contact with the victim's skin?

Otherwise, as already suggested above, both live contacts could be incorporated into the pressure wrap so that the victim's arm completes the circuit.


*Why this obsession with water? Isn't water an insulator, a poor conductor of electricity?*

Yes. Pure or distilled water is an excellent electrical insulator, with a measured electrical resistivity of 18.2 million ohms per cm at 25C. And we'll come back to this.

Most water, and especially the water within our bodies, contains impurities. And the most important impurities are ions, electrically charged particles derived from reactive elements (elements which readily gain or lose electrons). 

Cations are positively charged metals - metal atoms which have lost or shed one or more of its valence (outer shell) electrons. Anions are negatively charged nonmetals - non metallic atoms which have gained one or more valence electrons. Together, they form salts - soluble, electrically neutral, ionic crystals with high melting points.

Salts are fully soluble in water, which means that the ionic bonds are lost and the cations and anions float freely in solution unless directed by an electromagnetic field. Salts in solution are good electrical conductors.

The human body is mostly salt water, salty enough to carry and transfer electrical energy. This is important because our body uses tiny electrical impulses to transfer information or directed action to every muscle and every organ. It is the dissolved salts, the ions in the body which transfers these impulses with minimal loss of energy.

The water, remember, is still electrically resistant, and resistance converts electrical energy to heat energy. That's why we can boil water with an electrical element in a jug.


Electrocuting someone, therefore, works in two ways: 
first, it overloads the normal electrical paths in the body, resulting in the loss of muscle control, muscle spasms and rigidity; and 
then, it adds heat to the water wherever it is in contact with the electrical overload current.


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