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Homework Help: AC circuit with two components given phase angle

  1. Mar 30, 2012 #1
    1. The problem statement, all variables and given/known data
    A circuit contains two elements, but it is not known if they are L, R or C. The current in this circuit when connected to a 1.20×101 V, 60.0 Hz source is 4.70 A and lags the voltage by 4.20×101 degrees.
    a) What are the two elements? (Answer A,B or C)

    2. Relevant equations
    Phasor diagram.
    w = 2pi*f
    tan(theta)=XL - XC / R

    3. The attempt at a solution
    From the phasor diagram for an AC circuit (or RLC circuit), usually the +y vector is for the inductor, the -y vector is for the capacitor, and the +x vector is for the resistor. Given that the phase angle is positive, I would say that the circuit is of type LR.
  2. jcsd
  3. Mar 31, 2012 #2


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    Homework Helper

    It is correct.

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