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!

Homework Help: Average power of a signal

  1. Oct 7, 2012 #1
    1. The problem statement, all variables and given/known data

    Find the average power of the signal,

    [tex]x_{1}(t) = 5cos(2\pi t + \frac{\pi}{10}) - 6sin(10t + \frac{\pi}{8})[/tex]

    2. Relevant equations

    3. The attempt at a solution

    [tex]P_{avg} = \frac{1}{T_{1}} \int_{0}^{T_{1}} 25dt + \frac{1}{T_{2}}\int_{0}^{T_{2}}36dt[/tex]

    [tex]P_{avg} = 61[/tex]

    The answer they list is,

    [tex]P_{avg} = \frac{61}{2}[/tex]

    Why are they using the RMS value of the signal as the magnitude?
  2. jcsd
  3. Oct 8, 2012 #2


    User Avatar
    Science Advisor
    Homework Helper

    hi jegues! :smile:

    eg 25*cos*sin = (25/2)*sin2, so its average is 25/2 :wink:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook