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Homework Help: Conceptual Question-Capacitance

  1. May 7, 2017 #1
    1. The problem statement, all variables and given/known data
    We start with a 2.50 μF capacitor connected to a power supply set to a voltage of 9.30 V. Then we increase the voltage on the power supply by 3.00 V. Now what is its capacitance?

    2. Relevant equations

    3. The attempt at a solution
    The answer is 2.5 μF still, but WHY doesn't the capacitance change when the voltage changes?
  2. jcsd
  3. May 7, 2017 #2


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    Gold Member

    Why do you think it should? If you had a 10 ohm resistor across the power supply would you expect it to become 11 ohms if you increased the voltage?
  4. May 7, 2017 #3
    According to the equation Q=VC, if voltage increases, capacitance should too... I'm missing something here.... I apologize!
  5. May 7, 2017 #4
    Capacitance is not dependent on voltage nor charge though, only material/geometry. Which is why it doesn't change.
  6. May 7, 2017 #5
    Q is the charge.

    If you increase the voltage (V), the charge increases but the capacitance (C) stays constant.
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