# Series RCL Circuits

1. Jul 16, 2008

### kdrobey

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. Jul 16, 2008

### dude_

i bet that the power factor is just the phase difference btw inductor and capacitor voltages : )

3. Jul 16, 2008

### dude_

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?

4. Jul 16, 2008

### dude_

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.