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: Series RCL Circuits

  1. Jul 16, 2008 #1
    1. The problem statement, all variables and given/known data
    A series RCL circuit contains a 47.0 resistor, a 2.00 µF capacitor, and a 5.00 mH inductor. When the frequency is 2520 Hz, what is the power factor of the circuit?


    2. Relevant equations
    cos(angle)=Vr/Vo
    Vr=(IrmsR)
    Vo=IrmsZ


    3. The attempt at a solution
    I know power factor is the cos(angle), but i'm having trouble figuring out what this question is actually asking for
     
  2. jcsd
  3. Jul 16, 2008 #2
    i bet that the power factor is just the phase difference btw inductor and capacitor voltages : )
     
  4. Jul 16, 2008 #3
    at resonance the power dissipation is maximum (i mean if the source resistance is matched to R).. and the phase difference btw C and L voltages is 90 degrees. which makes a power factor of cos90 = 0?
     
  5. Jul 16, 2008 #4
    ok i get it know theta is defined as (pi/2 - phi). phi being the phase difference btw C and L voltages. and at resonance, phase difference is pi/2 and that makes power_factor = 1 = Vr/Vo, which implies that all of the source voltage (Vo) is observed on the resistance (Vr), which was expected, since at resonance C and L cancels each other.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook