Q- meter is based on characteristics of 

Explanation:

Q-Meter

Definition: A Q-meter is an instrument used to measure the electrical properties of inductors and capacitors, specifically focusing on the quality factor (Q) of a circuit. The quality factor is a measure of the sharpness of resonance in a circuit and is mathematically defined as the ratio of the reactive power to the resistive power in the circuit. The Q-meter is primarily based on the principle of a series resonant circuit, where the resonance condition is utilized to calculate the Q-factor and other related parameters.

Working Principle: The Q-meter operates based on the characteristics of a series resonant circuit. In a series resonant circuit, resonance occurs when the inductive reactance (XL) and capacitive reactance (XC) cancel each other out, leaving only the resistive component to determine the circuit's impedance. At resonance, the current in the circuit reaches its maximum value, and the voltage across the inductor or capacitor becomes significantly larger than the applied voltage. This property is exploited in the Q-meter to measure the Q-factor and other parameters of the circuit or component under test.

Advantages of Series Resonant Circuit in Q-Meter:

• High Sensitivity: At resonance, the current in the circuit is maximized, making it easier to measure small variations in circuit parameters accurately.
• Direct Measurement: The Q-factor can be directly calculated using the voltage readings across the inductor or capacitor and the applied voltage.
• Simplicity: The series resonant circuit is simple in design and easy to implement in a Q-meter.

Applications of Q-Meter:

• Measurement of the Q-factor of inductors and capacitors.
• Determination of inductance and capacitance values.
• Testing and characterization of RF and microwave components.

Correct Option Analysis:

The correct option is:

Option 3: Series resonant circuit

This option is correct because the Q-meter relies on the properties of a series resonant circuit to measure the quality factor and related electrical parameters. At resonance, the impedance of the series circuit is purely resistive, and the current reaches its maximum value, enabling accurate measurement of the Q-factor and other parameters.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: Shunt resonant circuit

This option is incorrect because the Q-meter does not rely on the principles of a shunt resonant circuit. In a shunt resonant circuit, the components (inductor and capacitor) are connected in parallel, and the resonance condition results in a minimum impedance. This configuration is not suitable for Q-meters, which require the maximum current condition achieved in a series resonant circuit.

Option 2: Series-parallel circuit

This option is incorrect because a series-parallel circuit involves a combination of series and parallel connections of components, which complicates the resonance condition. The Q-meter specifically uses the simpler and more effective series resonant circuit to achieve accurate measurements.

Option 4: Inductive reactance circuit

This option is incorrect because an inductive reactance circuit alone does not provide the resonance condition required for the Q-meter's operation. The Q-meter relies on the cancellation of inductive reactance and capacitive reactance in a series resonant circuit to achieve accurate measurements.

Conclusion:

In summary, the Q-meter is a specialized instrument that utilizes the characteristics of a series resonant circuit to measure the quality factor and other electrical properties of inductors and capacitors. The series resonant circuit is ideal for this application due to its high sensitivity and simplicity. By understanding the principles of resonance and the operation of the Q-meter, engineers and technicians can accurately measure and analyze the electrical properties of various components and circuits.