**OSCILLATORS Questions with Answers :-**

**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**