What are the main differences between parallel and series resonance in AC circuits?

Definition:

Parallel Resonance: Parallel resonance occurs in an AC circuit when the total impedance of the parallel combination of inductance (L) and capacitance (C) becomes minimum. In a parallel resonance circuit, the current is at its maximum, while the voltage across the components is at a minimum.

Series Resonance: Series resonance occurs in an AC circuit when the total impedance of the series combination of inductance (L) and capacitance (C) becomes minimum. In a series resonance circuit, the voltage is at its maximum, while the current through the components is at a minimum.

Impedance Behavior:

Parallel Resonance: At parallel resonance, the impedance of the parallel combination of the inductor and capacitor becomes purely resistive. The reactive components cancel each other out, resulting in a low impedance value.

Series Resonance: At series resonance, the impedance of the series combination of the inductor and capacitor becomes purely resistive. The reactive components cancel each other out, resulting in a low impedance value.

Phase Relationship:

Parallel Resonance: In a parallel resonance circuit, the phase difference between voltage and current is maximum. The current leads the voltage by 90 degrees.

Series Resonance: In a series resonance circuit, the phase difference between voltage and current is minimum. The current and voltage are in phase with each other.

Frequency Response:

Parallel Resonance: At resonance, the frequency at which parallel resonance occurs is called the resonant frequency (fr). At this frequency, the current through the parallel combination is maximum.

Series Resonance: At resonance, the frequency at which series resonance occurs is also called the resonant frequency (fr). At this frequency, the voltage across the series combination is maximum.

Application:

Parallel Resonance: Parallel resonance is often used in applications where a high current at a specific frequency is required, such as in tuning circuits, band-pass filters, and impedance matching networks.

Series Resonance: Series resonance is utilized in applications where a specific voltage at a particular frequency is needed, like in radio receivers and transformers.

In summary, parallel resonance is characterized by minimum impedance and maximum current, while series resonance is characterized by minimum impedance and maximum voltage. Both resonance conditions have different applications and play essential roles in various AC circuit designs.