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HELP Capacitors in circuit

  1. Aug 17, 2009 #1
    HELP!!!Capacitors in circuit

    Hey guys, I have a short question here. If a resistor and a capacitor are connected in a series, it takes 2 seconds for the capacitor to to have a voltage of 2V, what happen to the voltage across the original capacitor if another same resistor is added in series? The answer is that it takes longer time for the voltage to reach 2V. I dont quite understand here since I thought the second resistor is gonna consume some voltage, so the voltage of the capacitor will drop.

  2. jcsd
  3. Aug 17, 2009 #2


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    Re: HELP!!!Capacitors in circuit

    Voltage can't be consumed. There is a voltage difference (or drop) across a resistor when current is flowing; the magnitude is proportional to the resistance and the current.

    At any finite time, the voltage across the capacitor is always lower in the second case, as you intuited. Eventually, though, the capacitor charges up to essentially the full supply voltage, and the current (and the voltage drops across the resistors) is zero. Does this help in figuring things out?
  4. Aug 17, 2009 #3
    Re: HELP!!!Capacitors in circuit

    The higher the resistance the smaller the charging current and so the longer the time it takes for the capacitor to charge.As charging proceeds the voltage across the capacitor increases as the current and the voltage across the resistive part of the circuit decrease.
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