Electrical – Relation between Resonant frequency and Resistance in series RLC circuit

capacitorcouplingfrequencypassive-networksresonance

schematic

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I have a series RLC circuit and I calculated the resonance frequency. Say its w (omega).

Now in second experiment, i use the resistor of half the value used in above ciruit. What effect will it have on my resonant frequency now?

Example:

Experiment 1: C = 100nF, L = 100mH, R = 100ohms

Experiment 2: C = 100nF, L = 100mH, R = 50ohms

Only resistor is changed. Nothing else.

Best Answer

What effect will it have on my resonant frequency

Theoretically it will have no effect on the resonant frequency. The resonant frequency is purely determined by the capacitor having exactly the opposite reactance of the inductor at a particular frequency and the two reactances cancel leaving the series tuned circuit having only resistance at resonance.

However, with lower values of resistance the peak shape of the resonance will change but the centre point of the peak will remain as previous.

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