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Finding current in a RLC circuit using kirchhoff laws

  1. Apr 10, 2012 #1
    1. The problem statement, all variables and given/known data

    Find current flowing through E1 ( find I1).

    2. Relevant equations

    I see 6 currents, atleast until the capacitor is charged, what i find confusing are the branches without any resistance and they seem to mess up my equations.

    3. The attempt at a solution
    1st kirchhoff's law
    I1+I5=I2
    I3+I6=I1
    I6+I5=I4
    2nd kirchhoff's law
    I2*L-I3*C=E1
    I2*L+R1*I5=E2
    I3*C+I6*R2=0

    In the end i get 2*I5-I6=5 which doesn't solve anything for me so I guess I'm still missing something there.
    Its been some time since I've done circuit calculations any help would be apritiated
     

    Attached Files:

  2. jcsd
  3. Apr 10, 2012 #2

    NascentOxygen

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    Staff: Mentor

    Are you after a steady-state DC analysis, or is this AC?

    If DC, then the inductor and capacitor can be replaced by a short-circuit and an open-circuit, resp.
     
  4. Apr 10, 2012 #3
    its a dc circuit right after commutation, the commutator switch is closed and is in series with E2 and R1 (i replaced it with a black line in the picture).
    Here i found an example, as i understand i have to calculate the currents in the exact moment when the condenser is being charged.
    any help with the equations would help allot.
    Thanks in advance
     

    Attached Files:

    Last edited: Apr 10, 2012
  5. Apr 10, 2012 #4

    gneill

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    Staff: Mentor

    :confused: E1 and R1 don't appear to be connected in your circuit. So where is this commutator?
     
  6. Apr 10, 2012 #5
    ow my bad! E2 I ment
     
  7. Apr 10, 2012 #6

    gneill

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    Staff: Mentor

    So to be clear, the circuit looks like this?
    attachment.php?attachmentid=46075&stc=1&d=1334077359.gif
     

    Attached Files:

  8. Apr 10, 2012 #7
    exactly
     
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