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Capacitor and pith ball

  1. Aug 6, 2015 #1
    Suppose I first charge a capacitor so that one plate is positively charged and another negatively. Now I remove the charging source and ground only one of the terminals say negative terminal, will there be a net positive charge in the capacitor that can be detected by a pith ball?
    Can a capacitor be used as static electricity generator?
     
  2. jcsd
  3. Aug 6, 2015 #2

    NascentOxygen

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    Staff: Mentor

    Grounding one of the terminals will have no effect on the charge on the plates, because with the other terminal connected nowhere, charge is unable to enter or leave the capacitor.

    A charged capacitor is a static source of electricity, but not a generator.
     
  4. Aug 7, 2015 #3
    Thanks...So if charged capacitor is source of static electricity, can it move the pith ball or attract small bits of paper like a charged balloon or charged comb does? is it possible to build a electrostatic levitator based on parallel plate capacitor?
     
  5. Aug 8, 2015 #4

    NascentOxygen

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    Staff: Mentor

    It's the voltage that is relevant to attracting pieces of paper. In principle, the voltage from a charged capacitor could be used, in place of a charged plastic comb; in practice you won't be able to easily demonstrate this at home because of the high voltage needed, probably a few thousand volts, at least. It is dangerous to try to produce and store voltages of that magnitude, except by techniques such as involving friction on a plastic comb.

    It is easy to overlook the high voltages associated with static electricity we experience daily around us. On dry winter's nights my fingertip can discharge a spark over a 0.5 cm air gap when reaching for canned items on the supermarket shelf!
     
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