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Homework Help: 1 uF Capacitor discharging into a 2uF capacitor

  1. Feb 20, 2012 #1
    This is a variant of the classic capacitor discharging into a capacitor problem and I’m having some trouble reasoning it out to my satisfaction…

    2 parallel capacitors (one 1 uF and one 2uF) with a switch and a 100 Ohm resistor between them. The 1 uF capacitor is charged to 100V and the 2 uF capacitor is discharged. I’m trying to draw plots of the voltage across each capacitor vs. time after the switch closes. I feel a bit stuck on the math for the unequal capacitor values and the impact on the time constants and voltage levels, but maybe I’m just over-thinking it. Thanks in advance for any insight.
  2. jcsd
  3. Feb 20, 2012 #2


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    Staff: Mentor

    Hi Lefty806, welcome to PF.

    You'll have to show the details of your current attempt(s) in order for us to see how to help you.

    EDIT: To start with, note that the capacitors are NOT actually in parallel since there is a resistor between one of the pairs of capacitor leads -- the capacitors are not actually connected to each other at both ends.
  4. Feb 20, 2012 #3
    Can you show your circuit diagram
  5. Feb 20, 2012 #4
    Thanks for already replying. I will post what.
  6. Feb 20, 2012 #5
    Sorry, mobile website mistake on my part...
    I will post what I can in regards to previous work and a schematic as soon as I can. Couple hours or so.
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