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Medical What voltage is normal for a human body?

  1. Jan 22, 2011 #1
    Does any one know what is normal voltage for a young, physically healthy human male?
    If you take a usual voltmeter and will ground the negative end how many millivolts do you suppose to read by touching dry human skin with the positive end?
    Is there suppose to be some difference between skin on your head and other body parts of between young and old people?Is there some difference when you are moving?
    If you body often accumulates charges up to 14 volts even if you are completely naked,especially when you make certain movements what anomality could be involved?Thanks
  2. jcsd
  3. Jan 22, 2011 #2


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    Staff: Mentor

    There is no such thing as voltage of the body.

    I am afraid your question is so off, it is not even clear where to start. Please learn a little bit about how the voltage is measured, when the voltage appears and what it means.
  4. Jan 22, 2011 #3
    I have to explain my question.I tried to experiment with voltmeter for a fan and I know basic princeples of it`s use.I remarked that when I ground the negative end of voltmeter and touch my dry skin with positive,voltage up to 14 volts may appear.But it doesn`t stay for a very long time and disappear.But with time it appears again.I do not wear synthetic cloth and according to my experiments it is not associated with some external triboelectrisity.It does appear even if I`m naked.I do not really know where those charges appear and how they accumulate.Maybe there is some electromagnetic activity in my appartment,who knows.I`m quite sure that I made mesurements correct,because also I correctly mesured voltage of different types of batteries in my appartment.
    I do not care if there is such thing as ``human voltage``,I`m just want to know what meanings on voltmeter you suppose to obtain if you did to a healthy person what I wrote above.
  5. Jan 22, 2011 #4


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    Staff: Mentor

    You need to be very careful here: reading a voltage between yourself and a ground wire of your house implies the ground is carrying a current. You can hurt yourself if your house's wiring is bad.

    Is your voltmeter on AC or DC? Try reading the neutral against the ground.
  6. Jan 22, 2011 #5


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    Staff Emeritus
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    If the OP is only measuring a transient voltage, that is likely nothing more than an artifact of local charge build up. That's not uncommon at all, and could be caused by any of several possible ways (e.g., walking on carpeted floor will rub off more charge than walking on a wood or stone floor, you pick up and retain more charge on a dry day than a humid one, etc.).
  7. Jan 22, 2011 #6
    Mostly I used metal casing of my PC as a ground and it`s working good.But not only PC.

    It`s on DC.

    Where exacly I need to conect?

    Possibly yes,but it appears in a room where is no carpet or any synthetic or wool things.
    I do not either wear any cloth from such materials.Posibly there is some leakage of electromagnetic energy,such a microwave owen or something...
    Last edited: Jan 22, 2011
  8. Jan 24, 2011 #7
    Voltage is a measurement of the difference in electrical potential between two points in a circuit.

    The concept of a "ground" can be confusing, many people will say "ground has zero volts." This doesn't make much sense as voltage must be compared between two things. You can say something is X volts higher than another thing, but you can't say something has X volts. "Ground" is an often arbitrary voltage value, you could just as easily consider the positive end of a battery "ground" and the negative end would have negative volts. If you consider the negative end "ground" then the positive end has positive volts.

    The ground in a plug should be connected to something that actually enters the actual ground outside or under your house. The ground at your house could have a higher potential than the ground at someone else's house. This is especially the case when they're further away from each other and if there's something environmental that may increase the voltage of the ground.

    You can even measure a potential voltage difference between different parts of your body. Though because your body is a fairly decent conductor any transient voltage differences even themselves out pretty quickly.

    Measuring the voltage between two things that aren't exactly part of the same circuit (such as you and the house's circuitry) will result in fairly useless data (and, if the difference is large, burnt-out-circuitry, which is especially bad if one of the circuits is biological in nature (ie, you)).

    Electricity is often described in terms of water in a pipe, in this metaphor voltage is the difference in height between the upper end of the pipe and the lower end. (you could also think of the somewhat arbitrary use of sea level as a measurement for the height of mountains as analogous to the electrical concept of "ground")
  9. Jan 24, 2011 #8
    any voltage you see has nothing to do with your health.

    if you have it set on AC, you may see some inductively-coupled voltage between the loop created by the meter leads and current in your mains power. on DC setting, you may see a few millivolts from chemical reactions between dissimilar metals of the leads and PC case, or the leads and your salts in your skin reacting.
  10. Jan 24, 2011 #9
    There's no way you have 14 volts between parts of your body unless you're wearing batteries. Maybe the meter is settling down when you take the reading.
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