# Electronics Engineering Mastery Test 17: ECE Pre-Board

(Last Updated On: April 4, 2021) This is 100 items set of Practice Examination 17 in Electronics Engineering composed of previous and/or potential Board Exams Questions. Read each questions and choices carefully! Choose the best answer. In the actual board, you have to answer 100 items in Electronics Engineering within 4 hours. You have to get at least 70% to pass the subject. Electronics Engineering is 30% of the total 100% Board Rating along with Mathematics (20%), General Engineering and Applied Sciences (20%) and Electronics Systems and Technology (30%).

#### Start the Test Yourself Exam 17

Choose the letter of the best answer in each questions.

1. What is the ratio of the input impedance with series feedback to that without feedback?

a. 1 + BA

b. BA

c. B

d. 1

Solution:

2. Which of the following is required to start oscillation?

a. BA > 1

b. The phase shift around the feedback network must be 180 degrees.

c. Both BA > 1 and the phase shift around the feedback network must be 180 degrees.

d. None of these

Solution:

3. Only the condition BA = _____ must be satisfied for self-sustained oscillations to result.

a. 0

b. -1

c. 1

d. None of these

Solution:

4. In the Wien bridge oscillator, which of the following is (are) frequency-determining components?

a. Both resistors

b. Both capacitors

c. Both resistors and capacitors

d. None of these

Solution:

5. In which of the following applications is a pulsating dc voltage suitable?

a. Battery charger

c. Stereo system

d. Computer

Solution:

6. Across which of the following components of a power supply does the average (dc) voltage exist?

a. Diodes

b. Secondary of transformer

c. Capacitor filter

d. None of these

Solution:

7. What is the purpose of an additional RC filter section in a power supply circuit?

a. Increase the dc voltage component

b. Increase the ac voltage component

c. Decrease the ac voltage component

d. None of these

Solution:

8. _______________ allows simplifying a one-port circuit to a current source in parallel with an impedance.

a. Norton’s Theorem

b. Thevenin’s Therorem

c. Kirchoff’s Current Law

d. Faraday’s Law of Magnetic Induction

Solution:

9. Charge carriers move in semiconductors via two mechanisms: _____ and _______.

a. drift and diffusion

b. drift and avalanche

c. avalanche and diffusion

d. none of these

Solution:

10. The ___________ is the minimum energy required to dislodge an electron from its covalent bond.

a. barrier potential

b. bandgap energy

c. potential energy

d. diffusion energy

Solution:

11. Under a high reverse bias voltage, pn pn junctions break down, conducting a very high current. Depending on the structure and doping levels of the device, ____________ breakdown may occur.

a. Zener

b. Avalanche

c. Drift

Solution:

12. For proper operation, the____________________ is forward-biased and the _____________________ is reverse-biased.

a. base-emitter junction, collector-emitter junction

b. base-emitter junction, base-collector junction

c. collector-base junction, base-emitter junction

d. collector-emitter junction, collector-base junction

Solution:

13. The ________________ of the bipolar transistor consists of an exponential voltage-dependent current source tied between the collector and emitter, and a diode (accounting for the base current) tied between the base and emitter.

a. r-parameter model

b. h-parameter model

c. small signal-model

d. large-signal model

Solution:

14. The ______ stage provides a moderate voltage gain, a moderate input impedance, and a moderate output impedance.

a. common-drain

b. common-collector

c. common-base

d. common-emitter

Solution:

15. The ___________ provides a voltage gain less than unity, a high input impedance, and a low output impedance, serving as a good voltage buffer

a. emitter follower

b. common base

c. common emitter

d. common source

Solution:

16. A measure of the small-signal performance of voltage-dependent current sources is the _____________ defined as the change in the output current divided by the change in the input voltage.

a. impedance

b. conductance

c. transconductance

d. reluctance

Solution:

17. For what value of ID is gm equal to 0.5 gm0?

a. 0 mA

b. 0.25 IDSS

c. 0.5 IDSS

d. IDSS

Solution:

18. Which of the following transistor has depletion and enhancement types?

a. BJT

b. JFET

c. MOSFET

d. Diode

Solution:

19. The region to the left of the pinch-off locus is referred to as the _____ region.

a. saturation

b. cut-off

c. ohmic

d. None of these

Solution:

20. The drain current will always be one-fourth of IDSS as long as the gate-to-source voltage is _____ the pinch-off value.

a. one-fourth

b. one-half

c. three-fourths

d. None of these

Solution:

21. It is the insulating layer of _____ in the MOSFET construction that accounts for the very desirable high input impedance of the device.

a. SiO

b. GaAs

c. SiO2

d. HCl

Solution:

22. How many terminals can a MOSFET have?

a. 2

b. 3

c. 4

d. 3 or 4

Solution:

23. Which of the following FETs has the lowest input impedance?

a. JFET

b. DMOSFET

c. EMOSFET

d. None of these

Solution:

24. How many orbiting electrons does the germanium atom have?

a. 4

b. 14

c. 32

d. 11

Solution:

25. One eV is equal to _____ J.

a. 6.02 E23

b. 1.6 E–19

c. 6.25 E18

d. 1.66 E–24

Solution:

26. What unit is used to represent the level of a diode forward current?

a. pA

b. nA

c. A

d. mA

Solution:

27. Calculate the power dissipation of a diode having ID = 40 mA.

a. 28 mW

b. 28 W

c. 280 mW

d. undefined

Solution:

28. What does a high resistance reading in both forward- and reverse-bias directions indicate?

a. A good diode

b. An open diode

c. A shorted diode

d. A defective ohmmeter

Solution:

29. At what region of operation is the base-emitter junction forward biased and the base-collector junction reverse biased?

a. Saturation

b. Linear or Active

c. Cut-off

d. None of these

Solution:

30. For the BJT to operate in the saturation region, the base-emitter junction must be _____-biased and the base-collector junction must be _____-biased.

a. forward, forward

b. forward, reverse

c. reverse, reverse

d. reverse, forward

Solution:

31. Which of the following voltages must have a negative level (value) in any NPN bias circuit?

a. VBE

b. VCE

c. VBC

d. None of these

Solution:

32. Which of the following is referred to as the reverse transfer voltage ratio?

a. hi

b. hr

c. hf

d. ho

Solution:

33. The _____ model suffers from being limited to a particular set of operating conditions if it is to be considered accurate.

a. hybrid

b. re

c. Thevenin

d. None of these

Solution:

34. What is the unit of the parameter ho of a BJT?

a. Volt

b. Siemen

c. Ohm

d. Unitless

Solution:

35. What is the typical value of the current gain of a common-base configuration?

a. Less than 1

b. Between 1 and 50

c. Between `100 and 200

d. Undefined

Solution:

36. What does the negative sign in the voltage gain of the common-emitter fixed-bias configuration indicate?

a. The output and input voltages are 180º out of phase.

b. Gain is smaller than 1.

c. Gain is larger than 1.

d. None of these

Solution:

37. The _____ configuration is frequently used for impedance matching.

a. fixed bias

b. voltage-divider bias

c. emitter-follower

d. collector feedback

Solution:

38. When a diode is forward-biased, the anode:

A. Is negative relative to the cathode.

B. Is positive relative to the cathode.

C. Is at the same voltage as the cathode.

Solution:

D. Alternates between positive and negative relative to the cathode.

39. Zener voltage is also known as:

A. Forward breakover voltage.

B. Peak forward voltage.

C. Avalanche voltage.

D. Reverse bias.

Solution:

40.The forward breakover voltage of a silicon diode is:

D. Dependent on the method of manufacture.

Solution:

41. The capacitance of a varactor varies with:

A. Forward voltage.

B. Reverse voltage.

C. Avalanche voltage.

D. Forward breakover voltage.

Solution:

42. The most likely place you would find an LED would be:

A. In a rectifier circuit.

B. In a mixer circuit.

C. In a digital frequency display.

D. In an oscillator circuit.

Solution:

43.A photodiode, when not used as a photovoltaic cell, has:

A. Reverse bias.

B. No bias.

C. Forward bias.

D. Negative resistance.

Solution:

44.The output of a rectifier is:

A. 60-Hz ac.

B. Smooth dc.

C. Pulsating dc.

D. 120-Hz ac.

Solution:

45.Which of the following might not be needed in a power supply?

A. The transformer.

B. The filter.

C. The rectifier.

D. All of the above are generally needed.

Solution:

46. The part of a power supply immediately preceding the regulator is:

A. The transformer.

B. The rectifier.

C. The filter.

D. The ac input.

Solution:

47. If a half-wave rectifier is used with 117-Vrms ac (house mains), the average dc output voltage is about:

A. 52.7 V.

B. 105 V.

C. 117 V.

D. 328 V.

Solution:

48. If a full-wave bridge circuit is used with a transformer whose secondary provides 50 Vrms, the PIV across the diodes is about:

A. 50 V.

B. 70 V.

C. 100 V.

D. 140 V.

Solution:

49. A transformer secondary provides 10 Vrms to a voltage-doubler circuit. The dc output voltage is about:

A. 14 V.

B. 20 V.

C. 28 V.

D. 36 V.

Solution:

50. The ripple frequency from a full-wave rectifier is:

A. Twice that from a half-wave circuit.

B. The same as that from a half-wave circuit.

C. Half that from a half-wave circuit.

D. One-fourth that from a half-wave circuit.

Solution:

51. Voltage regulation can be accomplished by a Zener diode connected in:

A. Parallel with the filter output, forward-biased.

B. Parallel with the filter output, reverse-biased.

C. Series with the filter output, forward-biased.

D. Series with the filter output, reverse-biased.

Solution:

52. The term “semiconductor” arises from:

A. Resistor-like properties of metal oxides.

B. Variable conductive properties of some materials.

C. The fact that there’s nothing better to call silicon.

D. Insulating properties of silicon and GaAs.

Solution:

53. Which of the following is not an advantage of semiconductor devices over vacuum tubes?

A. Smaller size.

B. Lower working voltage.

C. Lighter weight.

D. Ability to withstand high voltages.

Solution:

54.The most common semiconductor among the following substances is:

A. Germanium.

B. Galena.

C. Silicon.

D. Copper.

Solution:

55. GaAs is a(n):

A. Compound.

B. Element.

C. Conductor.

D. Gas.

Solution:

56. The purpose of doping is to:

A. Make the charge carriers move faster.

B. Cause holes to flow.

C. Give a semiconductor material certain properties.

D. Protect devices from damage in case of transients.

Solution:

57. A semiconductor material is made into N type by:

C. Injecting electrons.

D. Taking electrons away.

Solution:

58.Which of the following does not result from adding an acceptor impurity?

A. The material becomes P type.

B. Current flows mainly in the form of holes.

C. Most of the carriers have positive electric charge.

D. The substance has an electron surplus.

Solution:

59. In a P-type material, electrons are:

A. Majority carriers.

B. Minority carriers.

C. Positively charged.

D. Entirely absent.

Solution:

60. Holes flow from:

A. Minus to plus.

B. Plus to minus.

C. P-type to N-type material.

D. N-type to P-type material.

Solution:

61.When a P-N junction does not conduct, it is:

A. Reverse biased.

B. Forward biased.

C. Biased past the breaker voltage.

D. In a state of avalanche effect.

Solution:

62. Holes flow the opposite way from electrons because:

A. Charge carriers flow continuously.

B. Charge carriers are passed from atom to atom.

C. They have the same polarity.

D. No! Holes flow in the same direction as electrons.

Solution:

63. If the reverse bias exceeds the avalanche voltage in a P-N junction:

A. The junction will be destroyed.

B. The junction will insulate; no current will flow.

C. The junction will conduct current.

D. The capacitance will become extremely high.

Solution:

64. Semiconductor devices equivalent to thyratrons are generally called

A. thyrector

B. thyristor

C. diac

D. ignitron

Solution:

65. One of the electronic semiconductor devices known as diac, function as

A. four terminal multi-directional switch

B. two terminal bi-directional switch

C. two terminal unidirectional switch

D. three terminal bi-directional switch

Solution:

66. Which of the trigger diodes has the highest holding voltage?

A. bidirectional-trigger diac

B. bidirectional-diode-thyristor diac

C. Shockley diode

D. thyrector

Solution:

67. General term of electronic devices used to control or trigger large-power switching devices.

A. thyristor

B. thyrector

C. break-over devices

D. triggering devices

Solution:

68. A four-element solid state device that combi9nes the characteristics of both diodes and transistors

A. varactor

B. zener diode

C. tunnel diode

D. SCR

Solution:

69. Find the two stable operating conditions of an SCR.

A. Conducting and non-conducting

B. Oscillating and quiescent

C. NPN conduction and PNP conduction

D. Forward conducting and reverse conducting

Solution:

70. How do you stop conduction during which SCR is also conducting?

A. remove voltage gate

B. increase cathode voltage

C. interrupt anode current

D. reduce gate current

Solution:

71. The voltage across the anode (A) and cathode (K) terminals of an SCR when conducting.

A. holding voltage

B. breakdown voltage

C. breakback voltage

D. trigger voltage

Solution:

72. The minimum amount of current needed for an SCR to conduct continuously.

A. holding current

B. triggering current

C. threshold current

D. average sustaining current

Solution:

73. A circuit used for voltage equalization during ON-OFF switching action of SCRs in series.

A. snubber circuit

B. crow-bar

C. clipper

D. clamper

Solution:

74. A three terminal device that behaves roughly like SCR, except that it can conduct current in either direction when at ON.

A. thyristor

B. SUS

C. SBS

D. GTO

Solution:

75. Which are the three terminals of a TRIAC?

A. Gate, anode 1 and anode 2

B. Gate, source and sink

C. Base, emitter and collector

D. Emitter, base 1 and base 2

Solution:

76. A thyristor that is very similar to an SCR except that it has low voltage and current ratings. It is very temperature stable, and is therefore suitable to be used as triggering device.

A. UJT

B. GTO

C. SBS

D. SUS

Solution:

77. Thyristor whose characteristic curve closely resembles that of SCR’s and SUS’s, except that its forward breakover voltage (+VBO) is not alterable, for the device has no gate terminal.

A. diac

B. thyrector

C. UJT

D. Shockley diode

Solution:

78. A UJT or unijunction transistor is a three terminal breakover-type switching device. Its three terminals are called base 1, base 2, and emitter. Though this is a transistor and has base and emitter terminals, this operates very different from a BJT and is not used as a linear amplifier. Its applications are for

A. timers and oscillators

B. signal generators

C. triggering control for SCRs and triacs

D. all of these

Solution:

79. A UJT has an internal resistances of RB1 = 6 KΩ and RB2 = 3 KΩ, what is its interbase resistance?

A. 2 KΩ

B. 3 KΩ

C. 6 KΩ

D. 9 KΩ

Solution:

80. For a unijunction transistor (UJT) to switch ON

A. the base 1 voltage should be greater than the peak voltage

B. the base 2 voltage should be greater than the peak voltage

C. the emitter voltage should be greater than the peak voltage

D. the voltage between the emitter and base 1 should be greater than the peak voltage when emitter being more positive

Solution:

81. Portion in the welding process interval during which the welding current is flowing is called ____________.

A. cool sub-interval

B. released interval

C. squeeze interval

D. heat sub-interval

Solution:

82. In automatic welding system, basically there are how many intervals?

A. 2

B. 5

C. 10

D. 15

Solution:

83. In automatic welding what do you call the first interval wherein the material to be welded are held together?

A. squeeze interval

B. weld interval

C. hold interval

D. standby interval

Solution:

84. After the squeeze interval, what comes next in an automatic welding system?

A. squeeze interval

B. weld interval

C. hold interval

D. standby interval

Solution:

85. During the welding or weld interval, when a welding current is flowing the system is said to be at

A. weld interval

B. cool subinterval

C. heat subinterval

D. hold interval

Solution:

86. The portion of the weld interval during which the current is absent

A. cool subinterval

B. heat subinterval

C. hold interval

D. standby interval

Solution:

87. After the welding interval, it goes to _________ interval wherein the electrode pressure is maintained on the metal surfaces.

A. cool subinterval

B. heat subinterval

C. hold interval

D. standby interval

Solution:

88. Next to hold interval is __________ interval in automatic welding system.

A. squeeze

B. cool

C. standby

D. release

Solution:

89. After the release interval in automatic welding, the system will go to

A. cool interval

B. squeeze interval

C. standby interval

D. hold interval

Solution:

90. Refers to the system that has no feedback and is not self correcting

A. Close-loop system

B. Coal slurry system

C. Feed forward control system

D. Open-loop system

Solution:

91. The system is ____________ if a position servo system does not respond to small changes in the input.

A. under stabilized

B. underdamped

C. stabilized

D. overdamped

Solution:

92. Industrial circuit or system that is not self-correcting

A. open-loop

B. closed-loop

C. system with feed back

D. non-servo

Solution:

93. What do you call a circuit or system that is self-correcting?

A. open-loop

B. closed-loop

C. system without feed back

D. servo

Solution:

94. Open-loop in control system means:

A. it has no feedback

B. it is not self-correcting

C. it is not self-regulating

D. all are correct

Solution:

95. In control system, closed-loop means:

A. it has feedback

B. it is self-correcting

C. it is self-regulating

D. all are correct

Solution:

96. When a closed-loop system is used to maintain physical position it is referred as

A. gyro system

B. feedback system

C. servo system

D. differential system

Solution:

97. In closed-loop system, what do you call the difference in the measured value and the set value or desired value?

A. error

B. differential voltage

C. potential difference

D. threshold

Solution:

98. The __________ are two of the most common mechanical configuration of industrial robots.

A. Spherical and pneumatic

B. Articulated arm and cylindrical

C. Spherical and hydraulic

D. Jointed-arm and electric

Solution:

99. One advantage of hydraulic actuator in industrial robots include _____________.

A. great force capability handling heavy loads

B. lower operating cost than the other type

C. low initial cost than the other type

D. clean-no oil leaks

Solution:

100. ____________ includes tow of the actuator type used in industrial robots.

A. Pneumatic and Jointed-arm

B. Hydraulic and Pneumatic

C. Electric and Spherical

D. Hydraulic and Cylindrical

Solution:

### Complete List of Electronics Engineering Pre-Board Exams

Electronics Engineering Pre-Board Exams
Module 1: Electronics Engineering Exam 1                   Answer key: EXAM 1
Module 2: Electronics Engineering Exam 2                   Answer key: EXAM 2
Module 3: Electronics Engineering Exam 3                   Answer key: EXAM 3
Module 4: Electronics Engineering Exam 4                   Answer key: EXAM 4
Module 5: Electronics Engineering Exam 5                   Answer key: EXAM 5
Module 6: Electronics Engineering Exam 6                   Answer key: EXAM 6
Module 7: Electronics Engineering Exam 7                   Answer key: EXAM 7
Module 8: Electronics Engineering Exam 8                   Answer key: EXAM 8
Module 9: Electronics Engineering Exam 9                   Answer key: EXAM 9
Module 10: Electronics Engineering Exam 10                   Answer key: EXAM 10