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Charged capacitor

  1. Oct 20, 2015 #1
    In this video:

    exactly in the 7:05, the narrator says that is dangerous to charge the inductor and disconnect it of the circuit and that is necessary provide anoter path for the current flow. The same phenomenon happens with a charged capacitor too? Is necessary provide a path for a charged capacitor, otherwise, there will be problem?
  2. jcsd
  3. Oct 21, 2015 #2


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    Back in the days of vacuum tubes, the power capacitors usually were charged up to 400 volts - and they self-discharged pretty slowly. So, even if you pulled the plug, you could get quite a jolt when trying to repair the equipment.

    So - yes, when fiddling around in electronics, discharging capacitors through a limiting resistor seems a good idea.
  4. Oct 21, 2015 #3
    I believe the answers to your questions are No and No... It is not the same phenomenon and it is not necessary to provide a path to a charged capacitor, in fact, often times that's the whole point to charge a capacitor and leave it charge for future use.
    The reason why it takes energy to pump current through an inductor is because your are exciting the electromagnetic field, but the inductor by itself does not have the ability to keep it and so at the end of operation of your device this energy will always tend to come back out and so you need to provide a path.
  5. Oct 22, 2015 #4


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    Just be very careful if you ever have to repair a power supply. Fortunately most large capacitors are "leaky" and will self discharge but not all. Some will retain quite high voltages for a long time after being switched off.
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