What Happens to Voltage in a Parallel LRC Circuit with a DC Source?

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Discussion Overview

The discussion revolves around the behavior of voltage in a parallel LRC circuit when connected to a DC source. Participants explore the implications of the circuit's components, particularly the inductor and capacitor, under DC conditions.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant notes that at DC, the capacitor behaves like an open circuit and the inductor like a short circuit, questioning the resulting voltage across the components.
  • Another participant asserts that with the inductor in short circuit mode, the voltage across both the capacitor and inductor should be zero, suggesting that the circuit is effectively shorted.
  • A different participant claims that in an RC circuit with a DC source, the voltages on the inductor and resistor are zero, while the voltage across the capacitor equals the source voltage (Vcc).
  • There is a discussion about whether the configuration is parallel or series, with some participants indicating that the behavior may differ based on the configuration and the time period considered.
  • One participant expresses confusion about the voltage across components in a parallel configuration, questioning if they should have the same voltage due to their arrangement.
  • Another participant acknowledges that their previous statements about series circuits were incorrect in the context of parallel RLC circuits, indicating a shift in understanding.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the behavior of the circuit, with multiple competing views regarding the voltage across the components and the implications of the circuit configuration. Some participants agree on certain points while others present conflicting interpretations.

Contextual Notes

Participants express uncertainty about the initial conditions and the long-term behavior of the circuit, highlighting the dependence on the configuration (parallel vs. series) and the time frame considered.

Firefox123
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quick question about RLC circuits...

Okay guys and gals...

I know this is a rather dumb question, but I don't have a lot of reference material where I am at currently (I am in Kuwait as part of Operation Iraqi Fredom)...so if someone could give me an answer I would appreciate it...

I should really know this but I just can't remember the answer and I am having a brain fart at the moment...

Here is the question...

If we have a simple parallel LRC circuit with a DC source, what would the voltage be in such a situation?

At DC the Capacitor behaves ideally like an open circuit and the inductor behaves ideally like a short circuit...so what exactly would happen in this situation?

What would the Capacitor/Inductor voltage be?

Thanks.


Russ
 
Last edited:
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since the inductor is in short circuit mode, the voltage of capacitor n inductor should be zero. this circuit is shorted! and this is not the purpose of RLC. RLC should be powered by an AC voltage in order to produce resonance response.
 
There is no current flow in an RC circuit with a DC source.

The voltages on the inductor and resistor are zero. The voltage across the Capacitor is Vcc.
 
tmwong said:
since the inductor is in short circuit mode, the voltage of capacitor n inductor should be zero. this circuit is shorted! and this is not the purpose of RLC. RLC should be powered by an AC voltage in order to produce resonance response.

Thanks for responding...

I realize that this is not the purpose of an RLC circuit...but I was wondering what would happen at DC voltage...

You seem to be implying that in this case the short circuit of the inductor causes the voltages over the resistor and cap to be zero...while the inductor efferctively "shorts" out all other components...

Is this conclusion correct?



Russ
 
enigma said:
There is no current flow in an RC circuit with a DC source.

The voltages on the inductor and resistor are zero. The voltage across the Capacitor is Vcc.

Hey enigma...thanks for the reply...

Okay...so you are saying that the cap will have Vcc while the resistor and inductor have zero voltage...since they are in parallel (at least it appears that they are) shouldn't they have the same voltage?

Or is this specific situation different because of the behaviour of the components?

Also...are you saying that the inductor will have zero current flowing through it?

Your conclusion seem to contradict the other reply in this thread...

Which one correctly describes the behaviour of this circuit?



Russ
 
There is some question about if you mean a parallel or serial configuration.
And it depends on what period of time you are talking about.
On initial turn on, current will flow in the resistor for either configuration.

Enigma is giving the long term operation in serial configuration.
Tmwong went for the parallel configuration.
 
NoTime said:
There is some question about if you mean a parallel or serial configuration.
And it depends on what period of time you are talking about.
On initial turn on, current will flow in the resistor for either configuration.

Enigma is giving the long term operation in serial configuration.
Tmwong went for the parallel configuration.

My original question was about parallel RLC circuits...

But this answer will do also...

So you are saying that for a series RLC combination at DC, after a long time the open circuit of the capacitor will cause no current to flow in the circuit...

While for the parallel RLC combination at DC, after a long time the short circuit of the inductor will cause zero voltage across all components since the circuit is shorted.

So in one case (series RLC at DC)the open circuit takes most of the voltage drop and prevents current flow...

And in the other case (parallel RLC at DC) the short circuit shorts out the entire circuit causing current to flow but with very little voltage drop across the components.

Am I understanding your answer correctly?



Russ
 
You seem to have it right.
 
Ah. Yes, yes. Sorry.

I was doing work with series RLC circuits this summer and had them on the brain, apparently. Everything I said is incorrect for parallel RLC's.
 
  • #10
NoTime said:
You seem to have it right.


Ah...good then.

This was what I expected would happen at DC, but I wanted to ask someone to make sure...Im glad my original answer seems correct.

Thanks for the confirmation.



Russ
 
  • #11
enigma said:
Ah. Yes, yes. Sorry.

I was doing work with series RLC circuits this summer and had them on the brain, apparently. Everything I said is incorrect for parallel RLC's.


Thanks for the answer enigma...this is what I originally thought but I wanted to get other opinions to make sure I wasnt screwing it up...

You say you were working with series RLC circuits...was this for work or are you a professor at a university?




Russ
 

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