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Conductors, are those which have free electrons... and because of this have same electric potential all over. But considering our body, which has many electrical voltage, current signals passing by in neurons, skeletal muscles(also the ones in heart creating dipole), etc, how are we being conductors... that is I meant, where are free charge originated in us.. Are just metal ions responsible for this ?

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  • $\begingroup$ Once a current is flowing through them, they do not have the same electric potential all over. It is precisely the potential difference that drives the current. $\endgroup$ – Martin Kochanski Jun 1 '16 at 11:50
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Conduction is the transport of charge, and it doesn't matter what the charge carriers are. In metals the charge carriers are, as you say, the conduction electrons. However in electrolyte solutions like saline the conductors are hydrated ions like $\textrm{Na}^+$ and $\textrm{Cl}^-\;.$

As far as electricity is concerned our bodies are basically just dilute electrolytes, so the (rather low) conductivity of the human body is due to transport of ions.

You mention conduction in nerves. This is a bit of a special case because the main action of nerves is not to conduct electricity but to propagate changes in electrical potentials. Describing the mechanism by which nerves work would be off topic here but is easily Googled.

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  • $\begingroup$ What I wanted to say is that there is always, potential difference in between any two points of skin, when measured... may be due to muscle activation, or something else unknown, then how can we be considered as conductors...(neglecting the one caused by EMF radiations). $\endgroup$ – Wupadrasta Santosh Sep 6 '15 at 9:49
  • $\begingroup$ @WupadrastaSantosh: In effect we contain lots of tiny batteries. So if you make a circuit that includes a human body your circuit has lots of batteries in it. This type of circuit conducts electricity just like any other circuit. You just need to add up the contribution to the EMF from all the batteries. $\endgroup$ – John Rennie Sep 6 '15 at 9:51
  • $\begingroup$ Cell membrane potential differences form batteries ? $\endgroup$ – Wupadrasta Santosh Sep 6 '15 at 10:09
  • $\begingroup$ @WupadrastaSantosh: a battery generates a potential difference by a chemical reaction. Your cells develop chemical potentials by a chemical reaction (lots of different reactions in fact). So they're generating a potential difference in basically the same way. $\endgroup$ – John Rennie Sep 6 '15 at 10:15
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Google it and you will get great answers for example :

PURE WATER DOES NOT CONDUCT ELECTRICITY. It's all the salts and impurities in it that cause it to carry current. Skin is actually a very good insulator as well so, relative to metal, humans aren't very good conductors. However, it is things such as the ionized water and whatnot that make up our body that do cause us to conduct.

Actually the body is not too good. That is the reason that you get a shock as your body is a resistance not in fact a pure condutor. If you get an ordinary electricity multimeter and test your restance from one hand to another you will see that it is in fact quite high. That is reason that you cannot feel 12volt. Now when the body surface is moist then you get a greater contact area and the body resistance will drop hence putting a battery across your toungue induces a tingle.

Humans are actually horrible conductors. The typical resistance of any human is about 6 Meg Ohms. Copper is only a few ohms (depending on the length). But we do conduct because we are 70% water, (though pure water wont conduct electricity either.)

Source : yahoo answers

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    $\begingroup$ Although be careful: once a path is established through the skin (essentially dead keratin layer), our conductivity, as sacks of hydrated ions, is not that bad at all. Very large currents can flow from hundreds of volts, low impedance sources. Sometime, if these currents are confined to muscles in the limbs, they feel sore and numb for a while, but don't give any real indication of a serious injury until gangrene shows itself. $\endgroup$ – WetSavannaAnimal Sep 6 '15 at 10:05
  • $\begingroup$ Yahoo answers is flat out wrong. Pure water does conduct electricity, even though it is not a "good" conductor. The reason is that even in pure water there is a concentration of protons and hydroxyl ions. See the definition of pH. $\endgroup$ – CuriousOne Sep 6 '15 at 10:36
  • $\begingroup$ @CuriousOne does it then follow that hot water conducts better than cold water, because the hotter, the more ions? And that high voltage is mainly needed to initiate the flow of current? $\endgroup$ – Archimedix Sep 6 '15 at 22:54
  • $\begingroup$ @Archimedix: The ion concentration of water at 100 degrees Celsius seems to be about 7 times higher than at 25 degrees, so I would expect the conductivity to be that much higher. It does not take a large voltage to make ionic conduction happen, but there are complex charged double-layer effects on electrodes and at high enough voltage there is electrolysis which causes a non-trivial voltage/current curve of electrochemical systems. $\endgroup$ – CuriousOne Sep 7 '15 at 2:18

protected by Qmechanic Jun 1 '16 at 6:06

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