Advanced Problems on Q Meter

Electrical Measurements

This set of Electrical Measurements & Measuring Instruments Multiple Choice Questions & Answers (MCQs) focuses on “Advanced Problems on Q Meter”.

1. Q meter operator is the principle of __________
a) Series resonance
b) Current resonance
c) Self-inductance
d) Eddy currents

2. In a Q Meter, the values of tuning capacitor are C3 and C4 for resonant frequencies f3 and 2f4 respectively. The value of distributed capacitance is?
a) C3−C42
b) C3−2C43
c) C3−4C43
d) C3−3C42

3. A circuit tuned to a frequency of 1.5 MHz and having an effective capacitance of 150 pF. In this circuit, the current falls to 70.7 % of its resonant value. The frequency deviates from the resonant frequency by 5 kHz. Q factor is?
a) 50
b) 100
c) 150
d) 200

4. A circuit tuned to a frequency of 1.5 MHz and having an effective capacitance of 150 pF. In this circuit, the current falls to 70.7 % of its resonant value. The deviates from the resonant frequency are 5 kHz. Effective resistance of the circuit is?
a) 2 Ω
b) 3 Ω
c) 5.5 Ω
d) 4.7 Ω

5. Q Meter is used to measure _________
a) Q factor of an inductive coil
b) Only the effective resistance
c) Only bandwidth
d) Q factor of an inductive coil, the effective resistance, and bandwidth

6. Q factor of a coil measured by the Q Meter is _________ the actual Q of the coil.
a) Equal to
b) Same but somewhat lesser than
c) Same but somewhat higher than
d) Not equal to

7. Consider a circuit consisting of two capacitors C1 and C2. Let R be the resistance and L be the inductance which are connected in series. Let Q1 and Q2 be the quality factor for the two capacitors. While measuring the Q value by the Series Connection method, the value of the Q factor is?
a) Q = (C1–C2)Q1Q2Q1C1–Q2C2
b) Q = (C2–C1)Q1Q2Q1C1–Q2C2
c) Q = (C1–C2)Q1Q2Q2C2–Q1C1
d) Q = (C2–C1)C1C2Q1C1–Q2C2

8. Consider a circuit consisting of two capacitors C1 and C2. Let R be the resistance and L be the inductance which are connected in series. Let Q1 and Q2 be the quality factor for the two capacitors. While measuring the Q value by the Parallel Connection method, the value of the Q factor is?
a) Q = (C1–C2)Q1Q2Q1C1–Q2C2
b) Q = (C2–C1)Q1Q2Q1C1–Q2C2
c) Q = (C1–C2)Q1Q2Q2C2–Q1C1
d) Q = (C2–C1)C1C2Q1C1–Q2C2

9. Consider the following statements regarding the sources of error in a Q Meter.

i) If a coil with a resistance R is connected in the direct measurement mode and
If the residual resistance of the Q Meter is 0.1 R, 
Then the measured Q of the coil would be 1.1 times the actual Q.
ii) If the inductance to be measured is less than 0.1 μH.
The error due to the presence of residual inductance cannot be neglected.
iii) The presence of a distributed capacitance modifies the effective Q of the coil.

Which of the above statements are correct?
a) i, ii and iii
b) i and ii
c) ii and iii
d) i and iii

10. The function of the Q- Meter is to _________
a) Measure capacitance
b) Measure inductance
c) Measure quality factor of capacitor and inductor
d) Measure form factor of capacitor and inductor

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