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Homework Help: How to draw a phasor addition on AC circuit?

  1. Jul 16, 2012 #1
    How to draw a phasor ?

    1. The problem statement, all variables and given/known data

    Two alternating currents are applied out of phase with each other. One is 4 volts and the other is 3 volts 27° out of phase.

    These can be written as (4, 0°) and (3, 27°)

    2. Relevant equations

    a)draw both phasors
    b)draw the combined phasor between (0 degree and 360 degree)
    c)label peak voltage and state its value

    3. The attempt at a solution

    a)A rough drawing on paint http://imageshack.us/photo/my-images/3/plotb.jpg/

    b) I know A= 6.8106 volts by using this formula


    r=3cos27 + 4i + i(3sin 27)

    r=√(3cos27 + 9)2 + (3sin27)2


    Last edited: Jul 16, 2012
  2. jcsd
  3. Jul 16, 2012 #2


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    Staff Emeritus
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    Gold Member

    The drawing look OK, but I don't think you've got the right components. The real parts of the phasors are 4 and 3cos27 respectively. The imaginary parts are 0 and 3sin27 respectively.
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