Q factor for a parallel resonant circuit

Discussion in 'General Electronics Chat' started by mentaaal, Mar 11, 2008.

1. mentaaal Thread Starter Senior Member

Oct 17, 2005
451
0
Hey guys, I have the misfortune of having a TERRIBLE AC circuits lecuturer and he cant even tell me how to calculate the Q factor for a parallel resonant circuit. He told me that the formula to do this is: R(C/L) but what i want to know is how do you take into account all the resistances. Say for example, in my Lab experiment we had a parallel resonant circuit with 1kohm resistor in one lane, a capacitor in another and an inductor in the last lane. Each component also had a series 10 ohm resistor so the voltages and phases could be read with an oscilloscope. How do i calculate the Q factor of this circuit?

2. mik3 Senior Member

Feb 4, 2008
4,846
63
The correct formula for the Q factor is Q=R*(sqrt(C/L))

Now, the general formula for the Q factor is Q=(reactive power/average power)

the average power is the average power dissipated on the resistors
and the reactive power is the power stored by the capacitor or the inductor

3. S_lannan Active Member

Jun 20, 2007
247
2
if your lecturer is doing a crap job make a complaint.

you pay a lot of money to goto university / college.

if the teacher cannot do his job, you shouldnt have to suffer.

4. mentaaal Thread Starter Senior Member

Oct 17, 2005
451
0
Thanks for the reply, sorry about at i forgot to stick int the sqrt into the formula. Ok that makes sense but how do i calculate the q factor by the formula alone? What does R signify in this istance and how do all the other series resistors get taken into account in this formula?