Parallel Resonance

Definition

Parallel resonance, also known as anti-resonance, occurs in an AC circuit when the inductive and capacitive reactances are equal, causing the impedance of the circuit to be maximized. This results in a sharp peak in the circuit's response at the resonant frequency.

5 Must Know Facts For Your Next Test

1. In a parallel RLC circuit, parallel resonance occurs when the inductive and capacitive reactances are equal, causing the impedance to be maximized.
2. At the resonant frequency, the circuit behaves like a pure resistor, with the current and voltage in phase.
3. Parallel resonance is often used in radio frequency (RF) circuits, such as in radio receivers and transmitters, to select specific frequency bands.
4. The quality factor (Q) of a parallel resonant circuit determines the sharpness of the resonance peak and the bandwidth of the circuit's response.
5. Parallel resonance can be used to create high-impedance circuits, which are useful for filtering and signal selection applications.

Review Questions

• Explain the relationship between the inductive and capacitive reactances in a parallel RLC circuit at the resonant frequency.
  • In a parallel RLC circuit, at the resonant frequency, the inductive and capacitive reactances are equal in magnitude but opposite in sign. This means that the net reactance of the circuit is zero, and the impedance of the circuit is maximized. As a result, the circuit behaves like a pure resistor, with the current and voltage in phase.
• Describe how the quality factor (Q) affects the behavior of a parallel resonant circuit.
  • The quality factor (Q) of a parallel resonant circuit determines the sharpness of the resonance peak and the bandwidth of the circuit's response. A higher Q indicates a sharper resonance peak and a narrower bandwidth, meaning the circuit is more selective in the frequencies it responds to. Conversely, a lower Q results in a broader resonance peak and a wider bandwidth, making the circuit less selective. The Q of a parallel resonant circuit is influenced by the resistance in the circuit, with lower resistance leading to a higher Q.
• Discuss the practical applications of parallel resonance in electronic circuits.
  • Parallel resonance is widely used in various electronic circuits, particularly in radio frequency (RF) applications. In radio receivers and transmitters, parallel resonant circuits are used to select specific frequency bands, allowing the desired signal to be isolated and processed. Additionally, parallel resonance can be utilized to create high-impedance circuits, which are useful for filtering and signal selection applications, such as in audio equipment and communication systems. The ability to maximize the impedance at the resonant frequency makes parallel resonance a valuable tool in the design of efficient and selective electronic circuits.

Related terms

Resonant Frequency: The frequency at which the inductive and capacitive reactances in a circuit are equal, leading to parallel resonance.

Impedance: The total opposition to the flow of alternating current in a circuit, including both resistance and reactance.

Quality Factor (Q): A measure of the sharpness of the parallel resonance peak, indicating the ratio of the resonant frequency to the bandwidth of the resonance.