This Portion of Electrical andElectronic Measurements and Measuring instruments contains High Frequency Measurements MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.
This Section covers below lists of topics.
- Resonance Methods
- Measurement of Inductance
- Measurement of Capacitance
- Measurement of Effective Resistance
- Resistance Variation Method
- Reactance Variation Method
- T Network
- Parallel Network
- Bridge Network
- Q Meter
PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE
1. The effective reactance of an inductive coil,
- Increases because of stray capacitances as the frequency increases
- Decrease because of stray capacitances as the frequency increases
- Remain the same irrespective of the increase in frequency even if stray capacitances are present
- None of the above.
B. Decrease because of stray capacitances as the frequency increases
2. The effective reactance of an inductive coil
- Increases due to stray series inductances as frequency increases
- decreases due to stray series inductances as frequency increases
- remain the same irrespective of the increase in frequency even if stray series inductances, are present
- none of the above.
A. Increases due to stray series inductances as frequency increases
3. The effective resistance of a coil at high frequencies is more than its d.c resistance on account of
- Skin effects
- Proximity effects
- Eddy current losses
- All the above.
D. All the above.
4. A series RLC circuit is used for measurement of inductance of a coil using resonant method. Resonance conditions are produced by varying the capacitance. A thermoelectric type ammeter is used in series with the circuit. Also an electronic voltmeter is connected across the tuning capacitor
- The conditions of resonance are more reliably indicated when the ammeter reads maximum
- The conditions of resonance are more reliably indicated when the voltmeter connected across the capacitor reads maximum
- The conditions of resonance are same when both ammeter and voltmeter read maximum
- The conditions of resonance are indicated when both ammeter and voltmeter read minimum
B. The conditions of resonance are more reliably indicated when the voltmeter connected across the capacitor reads maximum
5. If the Q factor of coil which is (w0 L)/R is measured by varying the frequency
- The plot between Q and frequency is linear
- The value of Q initially decreases with increase of frequency and afterwards increases with increase of frequency
- The value of Q will be increases with increase of frequency and afterwards decrease with increase of frequency
- The Q factor remains constant irrespective of the value of frequency.
C. The value of Q will be increases with increase of frequency and afterwards decrease with increase of frequency
6. The Q factor of a coil at the resonant frequency 1.5MHz of an RLC series circuit is 150. The bandwidth is :
- 225 MHz
- 1.06 MHz
- 10KHz
- None of the above.
C. 10KHz
7. The resonant frequency of an RLC series circuit is 1.5 MHz with the tuning capacitor set at 150pF. The bandwidth is 10 kHz. The effective resistance of the circuit is :
- 29.5 Ω
- 14.75 Ω
- 9.4 Ω
- 4.7 Ω
D. 4.7 Ω
8. In a Q meter, distributed capacitance of coil is measured by changing the capacitance of the tuning capacitor. The value of tuning capacitor are C1 and C2 for resonant frequencies f1 and 2f1 respectively. The value of distributed capacitance is :
- (C1-C2)/2
- (C1-2C2)/3
- (C1-4C2)/3
- (C1-3C2)/2
C. (C1-4C2)/3
9. The true value of Q of a coil is 245 and the measured value is 244.5. the ratio of distributed capacitance to self capacitance if the coil is
- 2.04 × 10 -3
- 1.002
- 0.997
- None of the above.
A. 2.04 × 10 -3
10. In a Q meter, the value of shunt resistance connected across the oscillator is typically of the order of :
- Ω
- mΩ
- µΩ
- kΩ
B. mΩ
