How paradoxical! A parallel circuit and a series circuit at the same time!A lossless parallel resonant circuit has only two nodes, in my example node p and ground (gnd symbol). You can only talk about the voltage at V(p) because by definition V(gnd) = 0.
There is only one voltage to display. The energy exchange is shown by the quadrature relationship between the voltage V(p) and the current I(L1). Note that this is a series circuit, so I(L1) = - I(C1).
Yes, the capacitor is in "parallel" with the inductor, hence only two electrical nodes in the ideal circuit.How paradoxical! A parallel circuit and a series circuit at the same time!
Hi,Thank you, MrAl
It's amazing that you still have your notes.
How is it so? I was thinking more in terms of this picture where capacitor in connected in the middle rather than an inductor. Thank you.
Half, or Full?...
So, I was right in saying that energy is exchanged twice between inductor and capacitor every half cycle. Thanks.
There is never any ambiguity if you mark one of the nodes (can be any of the circuit nodes) with a ground symbol, and follow the convention in post #16!...
If i tell you i have a circuit where we have just one 5v DC voltage source and once capacitor and the capacitor voltage we will call vL, what is the polarity of the capacitor voltage? You can not tell me because i did not yet assign any reference polarity to the capacitor voltage. Note it is a DC source yet you still cant tell me because we did not show how we wish to interpret that voltage yet.....
Hello,There is never any ambiguity if you mark one of the nodes (can be any of the circuit nodes) with a ground symbol, and follow the convention in post #16!
Please have a look on the attachment.Half, or Full?
Hi,Thank you, MikeMl, MrAl.
Please have a look on the attachment.
Point A: The capacitor has fully discharged. The inductor takes over and keep pushing the current in the same direction.
Point B: The magnetic field of indcutor has fully vanished and hence no more stored energy. The capacitor starts pushing the current in the other direction.
Point C: The capacitor has fully discharged and the inductor takes over and keeps the current flowing in the same direction.
Point D: The inductor has fully discharged and at this point the capacitor takes over.
The energy exchange takes place four time in a single cycle; therefore it was really "half cycle". Please let me know if I'm wrong. Thank you.
Hi,Thank you.
I think that it's a matter of viewpoint.
The energy exchange between electric field of capacitor and magnetic field of inductor takes place twice each cycle. As an analogy we can look at a pendulum example where energy exchange between potential energy and kinetic energy takes place twice. You can have a look here: https://www.allaboutcircuits.com/textbook/alternating-current/chpt-6/electric-pendulum/
From my viewpoint, energy exchange between the capacitor and inductor takes place four times each cycle but the exchange between 'electrically' stored energy and 'magnetically' stored energy takes place twice each cycle. Thanks a lot.
I'd refer back to my post #31.A total exchange means that at some point the cap has all the energy and at another point in time the inductor has all the energy.
Thank you, MrAl.
I'd refer back to my post #31.
How much energy does the capacitor have at point "A"? And how much energy does the inductor have at point "B"? Thanks a lot.
Your attempt to derive the resonant frequency with resistance present in the coil tells me that you do not quite understand the principle of parallel resonance (PR). Unlike series resonance, PR depends on the different amplitudes and phases of the currents in the branches. Lets start out with the admittance of the coil with resistance and capacitor without resistance in parallel.Hi,
Could you please help me with the question below?
Please have a look on the attachment. I'm not sure how they are getting to this final expression. I had thought that perhaps they started with the 'initial expression' and after simplification got this final expression but it looks like I was wrong. You can see below that I tried to simplifyy the initial expression but it ended up to something different from final expression. Thank you!
Note to self:
Q (the “quality factor”), is a measure of how much energy is not lost in a reactive element. The higher the Q, the less energy is lost. Quality factor exist for inductor as well as capacitor. Q_C=Xc/Rc=1/(2*pi*f*C*Rc) and Q_L=X_L/R_w=2*pi*f*L/Rw where Xc=1/(2*pi*f*C) is capacitive reactance, Rc is equivalent series capacitor resistance, X_L=2*pi*f*L and Rw is equivalent series winding resistance. When the resistance is just the winding resistance of the coil, the circuit Q and the coil Q are the same.
Helpful link(s): http://www.capacitorguide.com/q-factor/