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Homework Help: An RC Ciruit

  1. Oct 15, 2007 #1

    If a charged capacitor c=35 micro farads is connected to a resistor R=120 ohms how much time will elapse until the voltage falls to 10^6/D of its original max value?

    Ciruit contains a switch, resistor, emf and a capacitor in series.

    Relevant equations are Time constant= T=cR and V(Final)=V(initial) e^-t/cr

    I think it requires logarithms but i am not sure.

    Can you please help me how to answer this.
  2. jcsd
  3. Oct 15, 2007 #2
    Another question is:

    A circuit containing a switch, Vo, a capacitor and a bulb in series.

    The capacior is originally uncharged. Describe the behaviour of the bulb from the instant the switch is on until a long time later.

    I think there will be a delay for the bulb to emit light and then it will emit light getting slowly brighter as the capacitor is getting charged up.

    Is this right???
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