# Malvino: MCQ in Oscillators

(Last Updated On: February 7, 2020)

This is the Multiple Choice Questions in Chapter 23: Oscillators from the book Electronic Principles 7th Edition by Albert Malvino. If you are looking for a reviewer in Electronics Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

### Topic Outline

• MCQs in Theory of Sinusoidal Oscillation
• MCQs in Wien-Bridge Oscillator
• MCQs in Other RC Oscillators
• MCQs in Colpitts Oscillator
• MCQs in Other LC Oscillators
• MCQs in Quartz Crystals
• MCQs in 555 Timer
• MCQs in Astable Operation of 555 Timer
• MCQs in 555 Circuits
• MCQs in Phase-Locked Loop
• MCQs in Function Generator ICs

### Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1 . An oscillator always needs an amplifier with

• a. Positive feedback
• b. Negative feedback
• c. Both types of feedback
• d. An LC tank circuit

2. The voltage that starts an oscillator is caused by

• a. Ripple from the power supply
• b. Noise voltage in resistors
• c. The input signal from a generator
• d. Positive feedback

3. The Wien-bridge oscillator is useful

• a. At low frequencies
• b. At high frequencies
• c. With LC tank circuits
• d. At small input signals

4. A lag circuit has a phase angle that is

• a. Between 0 and +90 degrees
• b. Greater than 90 degrees
• c. Between 0 and -90 degrees
• d. The same as the input voltage

5. A coupling circuit is a

• a. Lag circuit
• b. Lead circuit
• c. Lead-lag circuit
• d. Resonant circuit

6. A lead circuit has a phase angle that is

• a. Between 0 and +90 degrees
• b. Greater than 90 degrees
• c. Between 0 and -90 degrees
• d. The same as the input voltage

7. A Wien-bridge oscillator uses

• a. Positive feedback
• b. Negative feedback
• c. Both types of feedback
• d. An LC tank circuit

8. Initially, the loop gain of a Wien-bridge oscillator is

• a. 0
• b. 1
• c. Low
• d. High

9. A Wien bridge is sometimes called a

• a. Notch filter
• b. Twin-T oscillator
• c. Phase shifter
• d. Wheatstone bridge

10. To vary the frequency of a Wien bridge, you can vary

• a. One resistor
• b. Two resistors
• c. Three resistors
• d. One capacitor

11. The phase-shift oscillator usually has

• a. Two lead or lag circuits
• b. Three lead or fagcircuits
• c. A lead-lag circuit
• d. A twin-T filter

12. For oscillations to start in a circuit, the loop gain must be greater than 1 when the phase shift around the loop is

• a. 90 degrees
• b. 180 degrees
• c. 270 degrees
• d. 360 degrees

13. The most widely used LC oscillator is the

• a. Armstrong
• b. Clapp
• C. Colpitts
• d. Hartley

14. Heavy feedback in an LC oscillator

• a. Prevents the circuit from starting
• b. Causes saturation and cutoff
• c. Produces maximum output voltage
• d. Means B is small

15. When Q decreases in a Colpitts oscillator, the frequency of oscillation

• a. Decreases
• b. Remains the same
• c. Increases
• d. Becomes erratic

16. Link coupling refers to

• a. Capacitive coupling
• b. Transformer coupling
• c. Resistive coupling
• d. Power coupling

17. The Hartley oscillator uses

• a. Negative feedback
• b. Two inductors
• c. A tungsten lamp
• d. A tickler coil

18. To vary the frequency of an LC oscillator, you can vary

• a. One resistor
• b. Two resistors
• c. Three resistors
• d. One capacitor

19. Of the following, the one with the most stable frequency is the

• a. Armstrong
• b. Clapp
• c. Colpitts
• d. Hartley

20. The material with the piezoelectric effect is

• a. Quartz
• b. Rochelle salts
• c. Tourmaline
• d. All the above

21. Crystals have a very

• a. Low Q
• b. High Q
• c. Small inductance
• d. Large resistance

22. The series and parallel resonant frequencies of a crystal are

• a. Very close together
• b. Very far apart
• c. Equal
• d. Low frequencies

23. The kind of oscillator found in an electronic wristwatch is the

• a. Armstrong
• b. Clapp
• c. Colpitts
• d. Quartz crystal

24. A monostable 555 timer has the following number of stable states:

• a. 0
• b. 1
• c. 2
• d. 3

25. An astable 555 timer has the following number of stable states:

• a. 0
• b. 1
• c. 2
• d. 3

26. The pulse width out of a one-shot multivibrator increases when the

• a. Supply voltage increases
• b. Timing resistor decreases
• c. UTP decreases
• d. Timing capacitance increases

27. The output waveform of a 555 timer is

• a. sinusoidal
• b. triangular
• c. rectangular
• d. elliptical

28. The quantity that remains constant in a pulse-width modulator is

• a. Pulse width
• b. Period
• c. Duty cycle
• d. Space

29. The quantity that remains constant in a pulse-position modulator is

• a. Pulse width
• b. Period
• c. Duty cycle
• d. Space

30. When a PLL is locked on the input frequency, the VCO frequency

• a. Is less than f0
• b. Is greater than f0
• c. Equals f0
• d. Equals fin

31. The bandwidth of the low-pass filter in a PLL determines the

• a. Capture range
• b. Lock range
• c. Free-running frequency
• d. Phase difference

### Complete List of MCQ in Electronic Principles by Albert Malvino

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1. Kalpana Patel
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