This set of Electrical Measurements & Measuring Instruments Multiple Choice Questions & Answers (MCQs) focuses on “Qmeter”.
1. Q factor is called __________
a) Quality factor
b) Quantity factor
c) Queen factor
d) Quarter factor
Explanation: Q factor is also known as Quality factor or storage factor. It is basically a ratio of the power stored in an element to the power dissipated in that element.
2. Q factor is also defined as the ratio of _______
a) resistance to reactance
b) reactance to resistance
c) power to voltage
d) current to power
Explanation: Q factor can also be obtained as the ratio of reactance to resistance of an element. For inductive element it is the ratio of XL to R and for a capacitive element it is the ratio of XC to R.
3. What is a Q meter?
a) quality meter
b) quantity meter
Explanation: Q meter is basically an instrument that is used for the measurement of electrical properties of capacitors and coils. It is also used as a laboratory instrument.
4. Q meter works on the principle of _______
a) barkhausen criterion
b) piezoelectric effect
c) parallel resonance
d) series resonance
Explanation: Q meter basically operates on the characteristics of a series resonant coil. In a series resonant circuit the voltage drop across the coil or a capacitor is equal to the applied voltage multiplied by its Q factor.
Explanation: Q factor in a series resonant circuit is given by the relation,
Q = XL⁄R = XC⁄R
where, R is resistance of the coil
XC is the capacitive reactance
XL is the inductive reactance.
Explanation: The applied voltage E is inversely proportional to the Q factor of a circuit and is given by the relation,
7. A practical Q meter consists of __________
a) Wien bridge oscillator
b) AF oscillator
c) RF oscillator
d) Crystal oscillator
Explanation: Practically a Q meter consists of a wide range RF oscillator with a frequency range of 50 kHz to 50 MHz. Oscillator acts as a source and delivers current to a low shunt resistance.
8. Voltage across the shunt is measured by ________
Explanation: A thermocouple is used for measuring the voltage across a shunt resistance in a practical Q meter. Electronic voltmeter is used for the measurement of voltage across a resonant capacitor.
Explanation: Coil inductance in a Q meter is given by the relation,
where, f is the frequency in Hz
C is the capacitance in F.
Sanfoundry Global Education & Learning Series – Electrical Measurements.
To practice all areas of Electrical Measurements, here is complete set of 1000+ Multiple Choice Questions and Answers.