Q meter circuit of series connection
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Explanation
The Q meter works on series resonant. The resonance is the condition exists in the circuit when their inductance and capacitance reactance are of equal magnitude. They induce energy which is oscillating between the electric and magnetic field of the capacitor and inductor respectively.
The Q-meter is based on the characteristic of the resistance, inductance and capacitance of the resonant series circuit. The figure below shows a coil of resistance, inductance and capacitance connected in series with the circuit.
In this Q meter input voltage E is Q times the voltage appears across the capacitor. Hence E=Q Ec so ,the voltmeter is calibrated for finding the value of Q factor.