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I recently bought a new dressing gown and I am experiencing a lot of static electricity build up when wearing it.

It got me thinking, where are those electrons coming from? I would have thought that if the robe is rubbing electrons off my body, then as a unit of (me + robe), we still have the same number of electrons (they just moved from me to the robe). So then why do I receive a shock every time I touch the metal taps in the bathroom?

Also any tips on preventing it appreciated! A friend mentioned something about surfactants in washing powder and suggested I wash it. Why would that help?

Note: There is a related question How To Avoid Getting Shocked By Static Electricity, but it only answers the 2nd part of the question, I've highlighted in bold the bit I'd like a physics explanation for.

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They have moved from you to the robe, but it's your body, with its normal electrostatic balance now gone, that is making the complete connection between the tap and say, a wet floor.

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  • $\begingroup$ So you are saying that you can't count me + robe as a single unit when it comes to the electrostatic balance? What happens to the extra electrons that are now on the robe? Presumably the robe is now -ve'ly charged? I'm also not sure about the part where you say "your body makes a connection between the tap and the floor", neither the tap nor the floor has an imbalance? $\endgroup$ – magritte Nov 11 '16 at 14:57
  • $\begingroup$ I have been thinking about this since I wrote the answer, and how it could happen. Any extra electrons on the robe should go to the outside of it. My bathroom taps have, since the house was built, a grounding/earth strap on them, in case somebody brings in an electric hairdryer and zaps themselves in a steam filled room. your body makes a connection between the tap and the floor", neither the tap nor the floor has an imbalance if you have a net charge, it will go to ground anywhere it has a path to do so. $\endgroup$ – user108787 Nov 11 '16 at 15:07
  • $\begingroup$ My experience in electrostatics, apart from the annoying static discharge part, is limited, and its a long time since I read up about it, but the rubbing of the robe starts the process, the electrons move out to the outer edge of the robe and your body is left with a positive charge, I think we could agree on that. That leaves your body, unless the robe rubs the ground, as the only path for the charge to travel. I was also thinking, if the robe touched something conducting, it could equalise, but still leave you with a charge. $\endgroup$ – user108787 Nov 11 '16 at 15:18
  • $\begingroup$ Seems pretty weird to me that a -ve'ly charged robe can sit on a person that has +ve charge without the system equalising unless there is an insulator between the two. I guess the robe material must be an insulator, whereas the tap is a conductor? Anyway thanks for taking the time I'll accept this as the answer! Cheers. $\endgroup$ – magritte Nov 12 '16 at 15:09
  • $\begingroup$ Yes, I was wondering where the insulator came into it....anyway, it's one surefire way to get woken up in the morning.....regards $\endgroup$ – user108787 Nov 12 '16 at 16:13
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It's due to a non-conservative force called friction. There are different types, like rubbing two sticks to start a fire, or when it comes to jackets, depending on the material, the sleaves interact with the torso part when you walk thus making friction.

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  • $\begingroup$ Sorry, yes I understand how static charge happens via friction, however I don't understand why there is an imbalance, if I still have the robe touching me are we not classed as one unit? $\endgroup$ – magritte Nov 11 '16 at 15:06
  • $\begingroup$ No, you are not "one unit" due to your thermal energy. Thermal energy is strongly related with friction. $\endgroup$ – QuantumSerbian Nov 11 '16 at 16:26

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