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Voltage dependent Current source

  1. May 18, 2013 #1
    1. The problem statement, all variables and given/known data

    Find Vout at t=0.782s (I already found Vout at t=0 s. It is 0 V.)

    2. Relevant equations

    3. The attempt at a solution
    First I found Vs = 9*sin(14*0.782)=-8.989817V (with t in radians)
    Since Rpi is in parallel with the Vs, its voltage Vpi also equals to -8.98917 V.
    Since the dependent source is I=10^-3*Vpi= -8.989817E-3 A, it is the same current traveling through the 1000 ohms resistor in the right loop.
    Using the equation: Vout=IR=8.989817E-3A*1000ohms=8.990V (Current is positive in this case since the current direction is opposite of the passive configuration. That is, it is going from - to + instead of + to -.)

    Apparently, my answer is wrong. Would any one please help me to see where I am doing wrong here? (I wonder how does the wire connect the two loops affect the situation. Is it possible that the R in Vout=IR is not 1000, but 1050 (50 ohms resistor in the left loop since both resistors might be in series?)

    Many thanks in advance!
    Last edited: May 18, 2013
  2. jcsd
  3. May 18, 2013 #2
    I tend to agree with you. The question did ask for V at t = 0 and at .782 msec. Did you submit both answers? The connecting wire will make no difference.
  4. May 18, 2013 #3

    Thanks barryj.

    Yes, I submitted 0 for t=0 s and it is correct.

    The only problem I have is Vout when t=0.782s.
  5. May 19, 2013 #4
    Problem solved! Thanks everyone.
  6. May 19, 2013 #5
    What was the answer???
  7. May 21, 2013 #6
    The answer is...

    It is --8.99 since the system wants to see students reverse the sign twice.
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