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.


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.

  • $\begingroup$ 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

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.

  • $\begingroup$ 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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