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I was sleeping in the dark when I reached over for my blanket. It slipped out between my fingers and made a light spark. I repeated in different parts of the blanket at least ten times. I can't understand why this is happening. I rubbed another blanket and my fingertips still sparked. Why does this happen?

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marked as duplicate by ACuriousMind, Kyle Kanos, John Rennie, Martin, Ryan Unger Aug 24 '15 at 13:32

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    $\begingroup$ Have a read of this: en.wikipedia.org/wiki/Static_electricity $\endgroup$ – user81619 Aug 23 '15 at 20:58
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    $\begingroup$ Also, being in the dark obviously means you can see tiny sparks much easier. It's a very common effect. If you walk across a carpet floor, the static charge caused by your shoes brushing the carpet will often discharge when you touch a grounded metal cupboard, and that really does hurt. $\endgroup$ – user81619 Aug 23 '15 at 21:16
  • $\begingroup$ static electricity, search on wiki $\endgroup$ – pwghost Feb 17 '16 at 12:28
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When you rub your fingertips along a blanket you are exchanging charged particles like electrons and in some cases molecules missing an electron. This is due to friction. If you notice your fingers will actually become very hot if you do this over and over.

These electrons are negatively charged and create what we call an electric field around them which attracts positive charge and repels negative charge.

Atoms are typically neutral meaning that they have equal numbers of positive and negative charges and so aren't attracted or repelled very much by the electrons you have built up on your fingers. The charge you have built up on your finger all combine to create a strong electric field close by but not enough to pull other electrons away from neutral atoms. So then how does the build up of charge create light?

Well, there are freely floating electrons and ions in the air due to cosmic rays and radio activity in the Earth ionizing the air. These particles can be accelerated to very high energies near a build up of charge like that on your finger. Your charged finger then pulls these free electrons in the air toward it and on there way they collide with atoms in the air. These collisions excite the atoms which then emit light to settle back down to a lower energy state. That is why sparks create light.

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