300+ TOP OSCILLATORS Questions and Answers pdf | MCQs

OSCILLATORS Questions with Answers :-

1. An oscillator converts ……………..

1. c. power into d.c. power
2. c. power into a.c. power
3. mechanical power into a.c. power
4. none of the above
   Answer : 2

2. In an LC transistor oscillator, the active device is ……………

1. LC tank circuit
2. Biasing circuit
3. Transistor
4. None of the above
   Answer : 3

3. In an LC circuit, when the capacitor is maximum, the inductor energy is ……….

1. Minimum
2. Maximum
3. Half-way between maximum and minimum
4. None of the above
   Answer : 1

4. In an LC oscillator, the frequency of oscillator is ……………. L or C.

1. Proportional to square of
2. Directly proportional to
3. Independent of the values of
4. Inversely proportional to square root of
   Answer : 4

5. An oscillator produces……………. oscillations

1. Damped
2. Undamped
3. Modulated
4. None of the above
   Answer : 2

6. An oscillator employs ……………… feedback

1. Positive
2. Negative
3. Neither positive nor negative
4. Data insufficient
   Answer : 1

7. An LC oscillator cannot be used to produce ……………….. frequencies

1. High
2. Audio
3. Very low
4. Very high
   Answer : 3

8. Hartley oscillator is commonly used in ………………

1. Radio receivers
2. Radio transmitters
3. TV receivers
4. None of the above
   Answer : 1

9. In a phase shift oscillator, we use …………. RC sections

1. Two
2. Three
3. Four
4. None of the above
   Answer : 2

10. In a phase shift oscillator, the frequency determining elements are …………

1. L and C
2. R, L and C
3. R and C
4. None of the above
   Answer : 3

11. A Wien bridge oscillator uses ……………. feedback

1. Only positive
2. Only negative
3. Both positive and negative
4. None of the above
   Answer : 3

12. The piezoelectric effect in a crystal is ……………

1. A voltage developed because of mechanical stress
2. A change in resistance because of temperature
3. A change in frequency because of temperature
4. None of the above
   Answer : 1

13. If the crystal frequency changes with temperature, we say that crystal has ………….. temperature coefficient

1. Positive
2. Zero
3. Negative
4. None of the above
   Answer : 1

14. The crystal oscillator frequency is very stable due to ………………. of the crystal

1. Rigidity
2. Vibrations
3. Low Q
4. High Q
   Answer : 4

15. The application where one would most likely find a crystal oscillator is ……………..

1. Radio receiver
2. Radio transmitter
3. AF sweep generator
4. None of the above
   Answer : 2

16. An oscillator differs from an amplifier because it ………

1. Has more gain
2. Requires no input signal
3. Requires no d.c. supply
4. Always has the same input
   Answer : 2

17. One condition for oscillation is ………….

1. A phase shift around the feedback loop of 180o
2. A gain around the feedback loop of one-third
3. A phase shift around the feedback loop of 0o
4. A gain around the feedback loop of less than 1
   Answer : 3

18. A second condition for oscillations is ……………….

1. A gain of 1 around the feedback loop
2. No gain around the feedback loop
3. The attention of the feedback circuit must be one-third
4. The feedback circuit must be capacitive
   Answer : 1

19. In a certain oscillator Av = 50. The attention of the feedback circuit must be …………

1. 1
2. 01
3. 10
4. 02
   Answer : 4

20. For an oscillator to properly start, the gain around the feedback loop must initially be

1. 1
2. Greater than 1
3. Less than 1
4. Equal to attenuation of feedback circuit
   Answer : 2

21. In a Wien-bridge oscillator, if the resistances in the positive feedback circuit are decreased, the frequency……….

1. Remains the same
2. Decreases
3. Increases
4. Insufficient data
   Answer : 3

22. In Colpitt’s oscillator, feedback is obtained …………….

1. By magnetic induction
2. By a tickler coil
3. From the centre of split capacitors
4. None of the above
   Answer : 3

23. The Q of the crystal is of the order of …………

1. 100
2. 1000
3. 50
4. More than 10,000
   Answer : 4

24. Quartz crystal is most commonly used in crystal oscillators because ………….

1. It has superior electrical properties
2. It is easily available
3. It is quite inexpensive
4. None of the above
   Answer : 1

27. ………….. is a fixed frequency oscillator

1. Phase-shift oscillator
2. Hartely-oscillator
3. Colpitt’s oscillator
4. Crystal oscillator
   Answer : 4

28. In an LC oscillator, if the value of L is increased four times, the frequency of oscillations is …………

1. Increased 2 times
2. Decreased 4 times
3. Increased 4 times
4. Decreased 2 times
   Answer : 4

29. An important limitation of a crystal oscillator is ……………

1. Its low output
2. Its high Q
3. Less availability of quartz crystal
4. Its high output
   Answer : 1

30. The signal generator generally used in the laboratories is ………….. oscillator

1. Wien-bridge
2. Hartely
3. Crystal
4. Phase shift
   Answer : 1

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