Find Phasor

Discussion in 'Homework Help' started by Marco foschi, Mar 9, 2015.

  1. Marco foschi

    Thread Starter New Member

    Mar 4, 2015
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    0
    upload_2015-3-9_21-10-55.png
    The result for this problem is: -12.5 Cos(2t-53.13°) A

    I've found :
    Zc=-5J
    Zl= J
    I(2)= -5/2 = -2,5 A over 2 ohm resistor

    Then I've found Vc+Vl+Vr(2ohm) = ((-5+1)*-2.5)-5 =-15V

    I found current through 1ohm resistor = -15V/1= -15 A

    So I have -15-(-2.5) = -12.5 A

    Is it correct my procedure?
    How can I find angle of 53.13° ??

    Thanks
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    745
    what is the frequency of the voltage?
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    The question attached in post #1 shows it to be 2 radians/sec.
     
  4. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Thats about 0.31Hz, at that frequency the capacitor will have a reactance of 5.1 Meg ohms, the inductor will be 1 ohm, i dont think any current will flow in the series circuit.
     
  5. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Check the capacitor value in the circuit. It's 0.1 Farad not uF. Wouldn't that give Xc=5 ohms ?
     
  6. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    Phasor contains magnitude and angle. I don't see where you are using phasors. That is why you don't have any way to find the angle.
     
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