Question

Q meter operates on the principle of:

• A. series resonance
• B. current resonance
• C. self-inductance
• D. eddy currents

Hint:

Remember, Q meters rely on resonance — specifically series resonance — to simplify the measurement of Q factor by maximizing current flow.

Answer 1

The Correct Option is A

A Q meter is a precision instrument used to measure the quality factor (Q) of coils and capacitors.
It functions based on the principle of series resonance, which occurs in a circuit when the inductive reactance and capacitive reactance cancel each other out.
At this point, the impedance of the circuit is purely resistive and minimal, allowing the current to reach its maximum value.
This condition is ideal for measuring the Q factor, which is defined as the ratio of reactive power to real power.
By tuning the circuit to resonance and knowing the applied voltage and voltage across the capacitor, the Q factor can be directly calculated using the formula:
\[ Q = \dfrac{V_C}{V} \]
Where $V_C$ is the voltage across the capacitor and $V$ is the applied voltage.
This technique provides high accuracy and simplicity in the measurement of inductors and capacitors.