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Why do our bodies stay neutral after combing our hair?

  1. Nov 15, 2016 #1
    **This is more a general understanding question rather than a homework question**
    1. The problem statement, all variables and given/known data

    So when you comb your hair trillions of electrons get transferred from your hair to your comb. So when trillions of electrons go missing how is your body able to maintain a neutral charge?

    2. Relevant equations
    I'm not certain that your body maintains a neutral charge; it was just said by my teacher in class.

    3. The attempt at a solution
    Perhaps because your grounded?
    With respects to the size and amount of electrons, perhaps a trillion of them is not very many so your body can balance it.
     
  2. jcsd
  3. Nov 15, 2016 #2

    Bystander

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    You have heard "crackling" from your comb? In dry weather in winter?
     
  4. Nov 15, 2016 #3
    Even with millions of electrons being transferred from you to the comb it is pretty insignificant as a single electron has a minuscule charge and even millions do not make a huge difference
    When you comb your hair or take off a shirt and it rubs against your hair electrons are transferred from you to the object, or the other way around perhaps, but most the time they jump back in order to even out the charge
    This is wear static electricity comes from
    It is not always felt as most the time the electrons are too few to cause any physical sensation but in cases like this there are enough to at least cause one to hear a soft crackling while combing their hair
    So in short the charges will automatically balance and the electrons will hope from object to object in order to do so
     
  5. Nov 15, 2016 #4

    haruspex

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    Certainly, if you are grounded that would explain it easily.
    Even if you are not grounded, there will always be ions in the air around you. If you become positively charged, what will happen?
     
  6. Nov 17, 2016 #5

    andrevdh

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    The hair raising demo with a Van De Graaff is done while the student stands on an insulating platform.
     
  7. Nov 17, 2016 #6
    Haven't you ever rubbed your shoes on the carpet, and touched somebody's hand to give them a static shock? Your body is definitely storing charge.

    It is fairly common for electronics companies to provide a budget for employee training and static protective gear (grounding, treated smocks, ionizers, static safe containers, etc.) to prevent damage to electronic components from static discharge. The voltage generated by certain simple tasks can be surprisingly high. Below is a sample I found. I believe it was saying that a 3000 V static shock is too low to even be felt. But some static-sensitive components can be damaged by much lesser voltages.

    Walking across a carpet: 1,500 to 35,000 Volts
    Crossing your legs: 300 Volts
    Walking over an untreated vinyl floor: 250-12,000 Volts
    Working at a bench: 700-6,000 Volts
    Vinyl envelope for work instructions: 600-7,000 Volts
    Picking up common plastic bag from bench: 1,200 - 20,000 Volts
    Work chair padded with polyurethane foam: 1,500 - 18,000 Volts
    Touching a door knob or metal object: 1,500 to 35,000 Volts
    Standing up from a chair: hundreds of Volts
     
  8. Nov 17, 2016 #7

    andrevdh

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    I would think that scuffing your shoes on the carpet and drawing a spark comes about by the insulating shoes getting charged and inducing a charge on your body, that is by pushing the conduction electrons away from your feet.
    You can then draw a spark from a sharp point on your body by sticking your finger out.
     
  9. Nov 17, 2016 #8
    I will be the first to admit that I don't know a lot about the process of static generation. I was addressing whether or not the body can hold a charge. But perhaps the point your teacher was making was that in the case of combing your hair, your hair and the comb and your body all make up a closed circuit and therefore, the overall net gain/loss is neutral. That may be a valid point.
     
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