1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to write 100 and -100 in phasor notaion

  1. Jun 12, 2013 #1
    1. Write the following signals in phasor notation: v7(t)=100, v8(t)=-100(

    2. Acos(wt + Θ) = Ae^(j Θ)

    3. I want to say 0 because its just a constant, if not then 1 because Θ=0. It seems to easy. Is it 0?
  2. jcsd
  3. Jun 12, 2013 #2


    User Avatar

    Staff: Mentor

    If it's an AC voltage with 0° phase shift, then the 100V source is just 100V ∠ 0°. The -100V source can be written as -100V, or alternatively, 100V ∠180°. Often, when the angle is 0 or 180 the shorthand 100V or -100V is adequate, so long as you make sure to specify clearly that it's a phasor value.

    EDIT: As rude man points out in his (the next) post, phasor magnitudes are generally taken to be RMS values. If your given values of 100 and -100 are peak values of the sinusoid, then convert to RMS.
    Last edited: Jun 12, 2013
  4. Jun 12, 2013 #3

    rude man

    User Avatar
    Homework Helper
    Gold Member

    If a voltage in the time domain is v(t) = v0 sin(wt + θ) then the phasor is
    V = (v0/√2)e.

    So your equation 2 is off by a factor √2 and in 3 if the voltages are dc then there is no phasor at all since there is no sinusoidal voltage.

    Phasors are applicable only for steady-state sinusoids.

    If v7 = 100 sin(wt) or -100sin(wt) then the above should provide you your answers.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: How to write 100 and -100 in phasor notaion