series L/C ?

Neither, under the stipulated conditions.

This looks like a homework problem. If you cannot do your own homework at this early phase of your EE education, I urge you to find another course of study. It won't get any easier, and if you have a hard time paying attention to this simple stuff, the later courses will completely mystify you.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
Reply to
Larry Brasfield
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The total theoretical impedance is 0. Thus, the only thing limiting the current is the impedance of the source, and the resistance of the components.

In order to figure out the voltage between the components, imagine that there is some resistance R between the inductor and capacitor. Thus, before capacitor, there is Zl + R, and after it's Zc. You want to figure out the voltage across the cap, so you use the voltage divider relation:

V = V0 * Zc / (Zc + Zl + R)

Where V0 is the voltage of the driving signal.

Since Zc = -Zl, they cancel, and we have

V = V0 * Zc / R

Zc and V0 are constant at a given frequency.

So, what happens to V as R -> 0?

--
Regards,
   Robert Monsen

"Your Highness, I have no need of this hypothesis."
     - Pierre Laplace (1749-1827), to Napoleon,
        on why his works on celestial mechanics make no mention of God.
Reply to
Robert Monsen

If the inductor and capacitor were perfect, you could have any finite voltage across each with essentially zero volts across the pair. Also if the parts were perfect, it would take infinite current to support 1 volt across them and they would have infinite voltage across each.

Real inductors and capacitors that have AC losses will have finite voltages across them with a finite voltage across the pair.

--
John Popelish
Reply to
John Popelish

Hi Group,

I have a series L/C circuit, which will be excited at the resonate frequency with a 1Vpp Sine Wave.

The reactance of the Inductor is j45 and the Capacitor is -j45 at this frequency.

The circuit is such that the inductor is connected to the sine source and the other side to the Cap, the cap is connected here to ground.

If I measure the voltage across the cap at resonate, will it be zero or some large number?

pdrunen

Reply to
PDRUNEN

As John pointed out, real components have losses in the form of series resistance. Also, real signal generators have source impedance: typically

50 ohms. So, in the real world, your series LC circuit is a series RLC circuit.

If the source impedance of the signal generator is 50 ohms, and the losses are 0.1 ohms, the total impedance in the circuit is 50.1 + j45 - j45 = 50.1. If the source e.m.f. is 1V, the current would be just under 20mA. From there, you can work out what the voltage drop across each component is.

If the series resistance was much less, the current could be quite large...

Reply to
Andrew Holme

The components that your prof put on the blackboard can be considered perfect components. The source voltage would have zero internal resistance and the one volt p-p will be accurate to the infinite decimal place. The problem was probably designed to force your thinking to phase concepts or the like; nothing really to solve mathematically. Tom

Reply to
Tom Biasi

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