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Homework Help: Switch in a circuit

  1. Mar 15, 2010 #1
    I'm a little confused about current flow/switches in circuits. Let's say two resistors are connected in parallel to a battery- if there is a switch between the two resistors on the negative terminal side, and the switch is opened, current won't flow through the second resistor, right? If current can't flow through there because there's no where for it to go, how come it can flow "into" a capacitor"?
     
    Last edited: Mar 15, 2010
  2. jcsd
  3. Mar 15, 2010 #2

    ehild

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    Could you please show the circuit diagram?

    ehild
     
  4. Mar 15, 2010 #3
    Something like this: http://www.gcsescience.com/Switches-Lamps-Parallel-Circuit.gif [Broken]

    if all other switches are closed but S4 is open, current won't flow through the last resistor, right? I didn't understand why but someone explained that it is because current has nowhere to go. I don't understand why, then, current can flow into a capacitor.
     
    Last edited by a moderator: May 4, 2017
  5. Mar 15, 2010 #4

    ehild

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    It is not capacitor but a battery in the picture. The current flows out of the + pole of the battery and back into the negative pole, and can go along the parallel ways through lamps L1 and L2, but if it "chooses" to go across L3 it can not, as the way is broken.

    ehild
     
  6. Mar 15, 2010 #5
    Yeah I know I'm just asking hypothetically?
     
  7. Mar 15, 2010 #6
    I believe it has something to do with how a capacitor only stores electrons. A capacitor works via the use of two plates; one hooked up to the positive terminal of say a battery and the other to the negative end. The electrons become stored in the plate attached to the negative terminal of the battery until it becomes equal to the voltage of the battery. If there happens to be a resistor, let's say a light bulb, in between the voltage source and the capacitor then the light bulb will light up (because the electrons flow from the battery to the plate in order to charge the plate) but, soon enough, the bulb will go out (because the plate is storing the electrons).
     
  8. Mar 15, 2010 #7
    a capacitor has a positively and negatively charged plate. One plate has charge flowing into while the other has charge flowing out of it. No current flows through the capacitor -- the charge flowing into it comes from the battery, and the charge flowing out of it comes from one of the previously neutral plates of the capacitor(leaving an effective charge due to holes).
     
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