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Homework Help: Complex power with loads

  1. Oct 4, 2012 #1
    1. The problem statement, all variables and given/known data

    1. A 400-V, 100-Hz source supplies power to a load. If the load absorbs 400+j30 VA of power, find the following: (2 pts each)
    a. The magnitude of current drawn by the load.
    b. The apparent power absorbed by the load.
    c. The power factor of the load.
    d. The impedance of the load.
    e. Sketch and label the power triangle.

    2. Relevant equations

    none given

    3. The attempt at a solution

    I just wanted to make sure I was starting this off in the right direction. I am looking at this problem as the complex power = 400+j30 VA. This would give me the average power is 200W, and reactive power is 30 VAR correct? I could then find the apparent power by taking √[(Avg. Power)^2 + (Reactive Power)^2].

    I could then find the power factor by taking the (average power) / (apparent power). I was wondering if you guys could let me know if this is heading in the right direction so far? Thanks.
  2. jcsd
  3. Oct 4, 2012 #2


    User Avatar

    Staff: Mentor

    How did you determine that the average power is 200W?
  4. Oct 5, 2012 #3
    For the Apparent Power, check you decimals
    for Power factor, remember arc-cos
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