Why would a plaster appear to be attracted to the body?

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Offline thedoc

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asked the Naked Scientists:
   Hi Chris,

I should listen more quickly and trust the audience more, though, since someone answered the question in the next episode! Thanks for making the show! I especially like when you talk about scientific results that have been established for a while. I'm listening from Kagoshima, Japan, by the way. Maybe you don't have that place on your list yet. And I have a question, too. A few days ago I injured my foot and had to use a plaster. I noticed that the plaster is drawn to the skin from a short distance (1 cm?) like a magnet is to metal. How can that be? It can't be electromagnetic and I thought intermolecular forces only act at a much shorter distance. And I'm certainly not heavy enough for noticeable gravitational attraction.

Richard
What do you think?
« Last Edit: 14/10/2016 14:23:02 by _system »

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Offline alancalverd

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Re: Why would a plaster appear to be attracted to the body?
« Reply #1 on: 14/10/2016 17:32:29 »
When you strip the protective plastic off a plaster, you induce static charges on both, just like rubbing your hair with a balloon. Now you throw away the protective strip and you are left with a charged plaster that sees your body as a large, uncharged object - or you may even have acquired the opposite charge of the strip - so there is an electrostatic attraction between the plaster and the body.

Some patients notice an interesting phenomenon in an x-ray department: they say they can "feel the radiation". If you remove a synthetic gown, nylon shirt or Crimplene trousers (I'm going back to the Sixties here!) you will generate a considerable charge that will leave your body hair erect. The x-ray beam ionises the air around you and this can discharge your body, so you feel the odd sensation of all the hair relaxing.
helping to stem the tide of ignorance