Need L and C to be in series in order to have a RLC series circuit?

In summary, yes, an R which is in parallel to the LC pair could be converted (with network transformation theorems) to being in series to it.
  • #1
Swapnil
459
6
Do you only need L and C to be in series in order to have a RLC series circuit? (So where you put R doesn't matter right?).
 
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  • #2
Strictly speaking no, the R should be in series with L and C too. Then again, an R which is in parallel to the LC pair could be converted (with network transformation theorems) to being in series to it.

So I guess there is really no straight answer to this question.
 
  • #3
Swapnil said:
Do you only need L and C to be in series in order to have a RLC series circuit? (So where you put R doesn't matter right?).

RLC series circuit implies that RL are in series & C is shunted to the ground, that again implies that we have a low-pass circuit of second order (capacitor provides an escape route for high frequency). Now interchanging R and L will have no affect on the circuit, since they are in series (circuit will have same fc etc.) But if you interchange L & C you will end up with a high-pass circuit, since the capacitor will exhibit high Xc for low frequencies and low Xc for high frequencies. So it does matter in how you arrange the L&C, but it doesn't matter in how you arrange the R&C.

P.S You can prove this by writing a transfer function for the both circuits (swapped R) using laplace and you'll end up the similar functions.
 
  • #4
Swapnil said:
Do you only need L and C to be in series in order to have a RLC series circuit? (So where you put R doesn't matter right?).

A series RLC circuit has all 3 elements in series. That's why it's called a "series RLC circuit" after all. Is there a context to this question?
 
  • #5
berkeman said:
A series RLC circuit has all 3 elements in series. That's why it's called a "series RLC circuit" after all. Is there a context to this question?
Its just that you have these equations for a series and a parallel RLC circuit so I was wondering if you have circuit which has any arbitrary configuration of a resistor, a capacitor, and an inductor, would you always be able to call it either a series or parallel RLC circuit?
 

1. What is the purpose of having L and C in series in an RLC series circuit?

The purpose of having L (inductance) and C (capacitance) in series in an RLC series circuit is to create a resonant circuit that can store and release electrical energy. This allows for precise control of the frequency of the circuit and can be used for various applications such as filtering, tuning, and amplification.

2. Can an RLC series circuit still function without L and C in series?

Yes, an RLC series circuit can still function without L and C in series, but it would not be considered a resonant circuit. The inductance and capacitance play crucial roles in creating the resonant behavior of the circuit, so without them, the circuit would not be able to store and release energy at a specific frequency.

3. How does the placement of L and C in an RLC series circuit affect its behavior?

The placement of L and C in an RLC series circuit is important because it determines the overall impedance of the circuit. When L and C are in series, their individual impedances add up, resulting in a higher overall impedance. This leads to a narrower bandwidth and a sharper resonant peak. On the other hand, when L and C are in parallel, their individual impedances cancel out, resulting in a lower overall impedance. This leads to a wider bandwidth and a flatter resonant peak.

4. Can L and C be replaced with other components in an RLC series circuit?

Yes, L and C can be replaced with other components in an RLC series circuit depending on the desired behavior. For example, an inductor can be replaced with a transformer or a capacitor can be replaced with a varactor diode to create a tunable circuit. However, these replacements may affect the overall impedance and resonance of the circuit.

5. Why is it important for L and C to be carefully selected in an RLC series circuit?

L and C must be carefully selected in an RLC series circuit to achieve the desired resonant frequency and impedance. If the components are not chosen correctly, the circuit may not function as intended or may introduce unwanted effects such as distortion or instability. Additionally, the tolerances and quality of the components can also affect the overall performance of the circuit.

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