Voltage across R, L and C vs AC Voltage source in RLC Series Circuit

In summary, at resonance, the voltage across R, L, and C in a series resonance circuit can be larger than the source voltage, which is counter-intuitive and does not happen in DC circuits. This can be compared to a swinging weight on a rope, where small periodic forces can generate a large swing displacement. In time-varying magnetic fields, there is no potential for the electric field due to Faraday's Law. A helpful analogy for this phenomenon is to think of pushing a swinging weight with a small force and displacement. Further information on this topic can be found in the lecture on EM field theory provided in the given webpage.
  • #1
Zahid Iftikhar
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One property of series resonance circuit is that at resonance, the voltage across circuit elements R,L and C may be larger than the source voltage. I can relate it to vector analogy where component vectors may have larger values than the resultant and the phenomenon is counter-intuitive. This does not happen in DC circuits where sum of voltage across circuit components is always equal to the source voltage. Any useful intuitive explanation of this effect please?
Characteristics of RLC Series Circuit.PNG
 
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A useful analogy for resonant excitation is to think about a swinging weight on the end of a rope, and you pushing it at the extreme of each swing with a small force and displacement with your fingertip.

As long as the losses are low for the swinging weight, it takes very small repetitive/resonant forces and small pushes from your fingertip to make it build up a large swing displacement -- much larger than the small periodic push amplitude of your fingertip...
 
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It's simply sloppy! Don't use such sloppy books! There's no voltage across an inductance, it's an EMF. In time-varying magnetic fields, there's no potential for the elctric field due to Faraday's Law, which is one of the fundamental Maxwell equations,
$$\vec{\nabla} \times \vec{E}=-\frac{1}{c} \partial_t \vec{B}.$$
 
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  • #4
vanhees71 said:
It's simply sloppy! Don't use such sloppy books! There's no voltage across an inductance, it's an EMF. In time-varying magnetic fields, there's no potential for the elctric field due to Faraday's Law, which is one of the fundamental Maxwell equations,
$$\vec{\nabla} \times \vec{E}=-\frac{1}{c} \partial_t \vec{B}.$$
Thanks. I need more help on this please.
 
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1. What is the difference between voltage across R, L, and C in an RLC series circuit and the AC voltage source?

The voltage across R, L, and C in an RLC series circuit is the voltage drop across each individual component due to the flow of current. This voltage drop is caused by the resistance, inductance, and capacitance of each component. On the other hand, the AC voltage source is the alternating voltage that is applied to the circuit and is responsible for driving the flow of current through the circuit.

2. How does the voltage across R, L, and C change with respect to frequency in an RLC series circuit?

The voltage across R, L, and C in an RLC series circuit changes with respect to frequency due to the impedance of each component. At low frequencies, the impedance of the inductor is low, causing most of the voltage to drop across the inductor. At high frequencies, the impedance of the capacitor is low, causing most of the voltage to drop across the capacitor. At the resonant frequency, the impedance of the inductor and capacitor cancel each other out, resulting in a higher voltage drop across the resistor.

3. What happens to the voltage across R, L, and C when the circuit is in resonance?

When the circuit is in resonance, the voltage across R, L, and C is at its maximum value. This is because the impedance of the inductor and capacitor cancel each other out, resulting in a lower total impedance. This lower impedance allows for a higher flow of current, resulting in a higher voltage drop across the resistor.

4. How does the phase difference between the voltage across R, L, and C and the AC voltage source change with frequency in an RLC series circuit?

The phase difference between the voltage across R, L, and C and the AC voltage source changes with frequency in an RLC series circuit due to the phase shift caused by the inductor and capacitor. At low frequencies, the inductor causes a phase shift of 90 degrees, while the capacitor causes a phase shift of -90 degrees. At the resonant frequency, these phase shifts cancel each other out, resulting in a phase difference of 0 degrees.

5. How does the voltage across R, L, and C change when the resistance in the circuit is increased?

When the resistance in the circuit is increased, the voltage across R, L, and C decreases. This is because the increased resistance causes a higher voltage drop across the resistor, resulting in less voltage available for the inductor and capacitor. This also affects the resonant frequency of the circuit, causing it to shift to a lower frequency.

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