50 TOP OSCILLATORS Questions and Answers pdf | MCQs

OSCILLATORS Questions and Answers pdf :-

1. An oscillator converts ……………..

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

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

LC tank circuit
Biasing circuit
Transistor
None of the above
Answer : 3

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

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

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

Proportional to square of
Directly proportional to
Independent of the values of
Inversely proportional to square root of
Answer : 4

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

Damped
Undamped
Modulated
None of the above
Answer : 2

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

Positive
Negative
Neither positive nor negative
Data insufficient
Answer : 1

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

High
Audio
Very low
Very high
Answer : 3

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

Radio receivers
Radio transmitters
TV receivers
None of the above
Answer : 1

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

Two
Three
Four
None of the above
Answer : 2

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

L and C
R, L and C
R and C
None of the above
Answer : 3

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

Only positive
Only negative
Both positive and negative
None of the above
Answer : 3

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

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

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

Positive
Zero
Negative
None of the above
Answer : 1

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

Rigidity
Vibrations
Low Q
High Q
Answer : 4

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

Radio receiver
Radio transmitter
AF sweep generator
None of the above
Answer : 2

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

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

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

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

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

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

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

1
01
10
02
Answer : 4

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

1
Greater than 1
Less than 1
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……….

Remains the same
Decreases
Increases
Insufficient data
Answer : 3

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

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

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

100
1000
50
More than 10,000
Answer : 4

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

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

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

Phase-shift oscillator
Hartely-oscillator
Colpitt’s oscillator
Crystal oscillator
Answer : 4

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

Increased 2 times
Decreased 4 times
Increased 4 times
Decreased 2 times
Answer : 4

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

Its low output
Its high Q
Less availability of quartz crystal
Its high output
Answer : 1

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

Wien-bridge
Hartely
Crystal
Phase shift
Answer : 1

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