# Electronics Engineering Mastery Test 18: ECE Pre-Board

(Last Updated On: April 4, 2021) This is 100 items set of Practice Examination 18 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 18

Choose the letter of the best answer in each questions.

1. What composes all matter whether a liquid, solid or gas?

a. Atoms

b. Electrons

c. Protons

d. Neutrons

Solution:

2. The Piezoelectric effect in a crystal is _____.

a. a voltage developed because of mechanical stress

b. a change in resistance because of temperature

c. a change of frequency because of temperature

d. none of the choices

Solution:

3. A unit impulse function on differentiation results in

a. unit doublet

b. unit triplet

c. unit parabolic function

d. unit ramp function

Solution:

4. In the JK flip-flop a High on the K input during the clock transition will yield an output of

a. Q=low

b. Q-toggle

c. Q=high

d. not possible to determine

Solution:

5. What class of operation has little use in general purpose amplifiers but is used in high frequency oscillators?

a. class A

class AB

c. class B

d. class C

Solution:

6. Feedback factor is always

a. less than 1

b. equal to 1

c. more than 1

d. zero

Solution:

7. Arrival of a clock signal at the clock inputs of different flip-flops at different times as a result of propagation delays.

a. clock transition

c. clock skew

d. none of the choices

Solution:

8. With double the number of turns by the same length and area, the inductance is

a. the same

B. doubled

c. quartered

Solution:

9. An ideal op-amp has

a. infinite input and output impedance

b. very low input and output impedance

c. low input impedance and infinite output impedance

d. infinite input impedance and zero output impedance

Solution:

10. What is the most important factor of a power transistor?

a. impedance matching

b. output resistance

c. mounting

d. heat dissipation

Solution:

11. Which of the following methods can be used for measuring power without using wattmeter?

i. One voltmeter, one ammeter

ii. Two voltmeters, two ammeters

iii. Three voltmeters

iv. Three ammeters

a. i and ii only

b. ii and iv only

c. I and iii only

d. iv only

Solution:

12. In a junction FET, the control electrode is usually the:

a. source

b. emitter

c. drain

d. gate

Solution:

13. It decreases the ripple voltage in the output of a DC generator and increases the output voltage.

a. interpoles

b. prime mover

c. compensating winding

d. multiple coil armature

Solution:

14. A material with a high dielectric constant:

a. acts to increase capacitance per unit volume

b. acts to decrease capacitance per unit volume

c. has no effect on capacitance

d. causes a capacitor to become polarized

Solution:

15. A toroidal-core coil:

a. has lower inductance than an air-core coil with the same number of turns

b. is essentially self-shielding

c. works well as a Loop stick antenna

d. is ideal as a transmission-line transformer

Solution:

16. The horizontal displacement on an oscilloscope CRT screen is usually measured in

a. frequency per unit division

b. current per unit division

c. time per unit division

d. voltage per unit division

Solution:

17. Vidicon and plumbicon operate on the principle of:

a. photoconduction

b. photoemission

c. photovoltaic

d. none of these

Solution:

18. If the frequency is greater than the power bandwidth,

a. slew-rate distortion occurs

b. a normal output signal occurs

c. output offset voltage increases

d. distortion may occur

Solution:

19. In a boost regulator, the output voltage is filtered with a

a. choke-input filter

b. capacitor-input filter

c. diode

d. voltage divider

Solution:

20. An amplifier has the following percent harmonic distortions; D2 = 10%, D3 = 5% and D4 = 1%. What is the amplifier % THD?

a. 5.33%

b. 11.22%

c. 16.0%

d. 22.11%

Solution:

21. Magnetic amplifiers are used for

a. voltage amplification

b. power amplification

c. current amplification

d. frequency amplification

Solution:

22. A dynamic memory generally contains ________.

a. row and column decoders

b. row decoders

c. no decoders

d. column decoders

Solution:

23. At dc, the reactance of a capacitor

a. is zero, in theory

b. is very small negatively

c. is very small positively

d. is negatively infinite, in theory

Solution:

24. In a dry cell, what will happen to the internal resistance as it aged?

a. decrease

b. increase

c. remains constant

d. decreases or increases, depends on the chemical composition

Solution:

25. Meters built into electrical and electronic devices used to monitor the operation of the devices.

a. Imbedded meters

b. Built-in meters

c. In-circuit meters

d. Metering devices

Solution:

26. Syntax checking or a program is done by another program in the computer is called

a. debugger

b. coder

c. compiler

d. processor

Solution:

27. A first-order active-filter stage has

a. one capacitor

b. two op amps

c. three resistors

d. a high Q

Solution:

28. The magnetic field of a bar magnet most closely resembles the magnetic field of

a. a horseshoe magnet

b. a straight current-carrying wire

c. a stream of electrons moving parallel to one another

d. a current-carrying wire loop

Solution:

29. An amplifier with a negative-feedback path at midband frequencies

a. Cannot oscillate because of the negative feedback

b. Can easily oscillate at higher frequencies

c. Will have magnetic oscillations

d. Will have a phase shift of 270° if uncompensated

Solution:

30. Which of the following is NOT one of the three distinct regions in the characteristic curve of a diode?

a. forward bias region

b. reverse bias region

c. breakdown region

d. saturation region

Solution:

31. Calculate the ripple voltage of a capacitor filter for a peak rectified voltage of 30 V, capacitor C = 100 μF, and a load current of 50 mA.

a. 3.21%

b. 2.10%

c. 5.85%

d. 4.30%

Solution:

32. The basic memory cell of dynamic RAM consists of

a. a capacitance

b. a transistor

c. a flip-flop

d. a transistor acting as a capacitor

Solution:

33. The zener current in a zener follower is

a. equal to the output current

b. smaller than the output current

c. larger than the output current

d. prone to thermal runaway

Solution:

34. A control system in which the output is related to the input by device parameters only.

a. Open-loop control system

b. Closed-loop control system

c. Servomechanism

d. Feedback Control system

Solution:

35. The two general types of heating methods in industrial electronics are ________.

a. frequency and induction heating

b. induction and dielectric heating

c. coil and dielectric heating

d. coil and frequency heating

Solution:

36. To reduce the distortion in a CE amplifier, reduce the

a. dc emitter current

b. base-emitter voltage

c. collector current

d. ac base voltage

Solution:

37. A relay is connected into a circuit so that a device gets a signal only when the relay coil carries current. The relay is probably

a. An AC relay

b. A DC relay

c. Normally closed

d. Normally open

Solution:

38. Electron mobility property of silicon at 300 K is approximately equal to ___________ m2/ V-s

a. 1.1

b. 0.135

c. 0.048

d. 45

Solution:

39. A magnetic drum:

a. is similar to a drum in the orchestra

b. stores data in grooves that run in circles around the drum head

c. is a cylinder with data recording tracks running around its circumference

d. stores data in grooves running lengthwise along the drum

Solution:

40. Most of the digital computer do not have floating-point hardware because

a. floating point hardware is costly

b. it is slower than software

c. it is not possible to perform floating point addition by hardware

d. of no specific reason

Solution:

41. A data sheet gives these JFET values: IDSS = 20 mA and pinch-off voltage is 5 volts. What is the gate-source cut-off voltage?

a. 15 volts

b. 10 volts

c. -5 volts

d. 5 volts

Solution:

42. If the two supply voltages are plus and minus 15 V, the MPP value of an op amp is closest to

a. 0

b. +15 V

c. -15 V

d. 30 V

Solution:

43. If the transient during switching of a power supply are to be studied, which oscilloscope will be preferred?

a. An ordinary oscilloscope with high frequency sweep generator

b. Dual beam oscilloscope

c. Dual storage oscilloscope

d. Storage oscilloscope

Solution:

44. The dropout voltage of standard monolithic linear regulators is closest to

a. 0.3 V

b. 0.7 V

c. 2 V

d. 3.1 V

Solution:

45. Convert (614)8 to decimal.

a. 400

b. 384

c. 392

d. 396

Solution:

46. The output waveform of a 555 timer is

a. sinusoidal

b. triangular

c. rectangular

d. elliptical

Solution:

47. The purpose of a pentavalent impurity is to

a. reduce the conductivity of silicon

b. increase the number of holes

c. increase the number of free electrons

d. create minority carriers

Solution:

48. What happens if the input capacitor of a transistor of a transistor amplifier is short-circuited?

a. biasing conditions will change

b. transistor will be destroyed

c. signal will not reach the base

d. biasing will stabilize

Solution:

49. Binary hardware computes division as:

b. multiplication

c. subtraction

d. none of these

Solution:

50. With both bases grounded, the only offset that produces an error is the

a. input offset current

b. input bias current

c. input offset voltage

d. Beta

Solution:

51. Suppose an ac signal has a frequency of 1770 Hz. What is its angular frequency?

d. impossible to determine from the data given

Solution:

52. X-rays are produced by

1. Bombarding metallic targets with high speed electrons

2. Decelerating fast moving electrons

3. Accelerating electrons to high speeds

4. Heating a filament to high temperature

a. 1 and 2 only

b. 2 and 4 only

c. 3 and 4 only

d. 1 and 4 only

Solution:

53. The sections of a basic isolation amplifier are

a. copper strips

b. transformers

d. current loops

Solution:

54. Which of the following is a dc bridge that is very useful for making extremely accurate voltage measurements?

a. Wheatstone bridge

b. Potentiometer bridge

c. Kelvin bridge

d. Owen bridge

Solution:

55. If the net reactance in a series coil-capacitor circuit is zero at frequency f, what will be the nature of the reactance at frequency 2f?

a. zero

b. inductive

c. capacitive

d. resistive

Solution:

56. A converter that changes ac-voltage to ac-voltage level

a. inverter

b. cycloconverter

c. dc-converter

d. ac converter

Solution:

57. What is the approximate short circuit current output of 741 op amp?

a. 15 mA

b. 30 mA

c. 25 mA

d. 35 mA

Solution:

58. Calculate the CMRR of a voltage follower whose common mode gain is 0.005.

a. 0.005

b. -46 dB

c. 1

d. 200

Solution:

59. Nodal analysis is best used together with

a. KVL

b. VDT

c. KCL

d. CDT

Solution:

60. A graph which shows the relationship between the armatures generated emf and the field excitation in terms of field current.

a. magnetization curve

b. hysteresis curve

d. regulation curve

Solution:

61. It is a robot structure wherein the body can rotate horizontally, and the arm can move vertically and horizontally.

a. polar structure

b. pivotal

c. cylindrical structure

d. roborat

Solution:

62. Series motors are also called _____.

a. synchronous motors

b. dc motors

c. induction motors

d. universal motors

Solution:

63. A single digital word storage device is called:

a. gate

b. clock

c. timer

d. register

Solution:

64. Which of the following is a good use, or place, for a wire wound resistor?

a. To dissipate a large amount of dc power

b. In the input of a radio-frequency amplifier

c. In the output of a radio-frequency amplifier

d. In an antenna, to limit the transmitter power

Solution:

65. Suppose that two capacitors are in parallel. Their values are 47.0 pF and 470.0 pF. What is the net capacitance of this combination?

a. 43 pF

b. 517 pF

c. 517 μF

d. 470 μF

Solution:

66.When Q factor of a circuit is high, then

a. Power factor of the circuit is high

b. Bandwidth is large

c. Impedance of the circuit is high

d. None of these

Solution:

67. Which of the items below is not true with a of a transistor?

a. it is the current gain of a common-base configuration

b. it is the ratio of the change in collector current to the change in emitter current

c. it is usually having a value of unity in some approximations

d. it is the ratio of the change in collector current to the change in base current

Solution:

68. A program loop:

a. is an input channel

b. is used to avoid repetition of a series of operation

c. is a circuit within a storage unit

d. is a programmed instruction that causes a series of operations to be repeated

Solution:

69. The configuration noted for its stability in RF power amplifiers

a. common emitter circuit

b. common base circuit

c. common collector circuit

d. emitter follower circuit

Solution:

70. A second order system exhibits 100% overshoot. Its damping coefficient is

a. equal to 0

b. equal to 1

c. less than 1

d. greater than 1

Solution:

71. A rule-based system is also known as

a. a logic gate

b. an expert system

c. a back-pressure sensor

d. a telechir

Solution:

72. Which of the following is not a characteristic of CMOS chips?

a. Sensitivity to damage by electrostatic discharge

b. Low current demand

c. Ability to work at high speed

d. Ability to handle extremely high power

Solution:

73. What will happen to the susceptance of a capacitor if the frequency is doubled and all other factor constant?

a. It will decrease to half its former value.

b. It will not change

c. It will double

Solution:

74. A ferromagnetic core is placed in an inductor mainly to

a. Increase the current carrying capacity

b. Increase the inductance

c. Limit the current

d. Reduce the inductance

Solution:

75. In an RC circuit, as the ratio Xc/R approaches zero, the phase angle

a. approaches -90 degrees

b. approaches zero degree

c. stays the same

d. cannot be found

Solution:

76. An autotransformer

b. has a center-tapped secondary

c. consists of a single tapped winding

d. is useful only for impedance matching

Solution:

77. Quartz crystal is the most commonly used in crystal oscillators because

a. it is easily available

b. it has superior electrical properties

c. it is quite expensive

d. it is very rugged

Solution:

78. A robot, car or truck can best keep itself traveling down a specific lane of traffic by means of

a. stereoscopic machine hearing

c. edge detection

d. proximity sensing

Solution:

79. Plastic dual in-line for insertion into sockets has a package suffix code of

a. N

b. P

c. N and P

d. J

Solution:

80. Calculate the permittivity of a material with relative permittivity of 5.

a. 8.854 x 10-11 F/m

b. 1/36π x 10-9 F/m

c. 4.42 x 10-11 F/m

d. 8.854 x 10-12 F/m

Solution:

81. What is the only input combination that will produce a high at the output of a five-input AND gate?

a. At least one low input

b. At least one high input

c. All inputs should be low

d. All inputs should be high

Solution:

82. The property of a material which opposes the creation of the magnetic flux.

a. elastance

b. permeance

c. susceptance

d. reluctance

Solution:

83. The ability of a tuned circuit to maintain oscillation.

a. Barkhaussen effect

b. Edison current

c. Flywheel effect

d. Tuned effect

Solution:

84. A high power, low frequency diode is normally _____ than a low power, high frequency diode.

a. heavier

b. smoother

c. larger

d. smaller

Solution:

85. Find the BCD equivalent of 1981 (binary code):

a. 000011110001

b. 11110011100

c. 110011000001

d. none of these

Solution:

86. The input impedance of a CRO is nearly

a. zero

b. around 10 ohms

c. around 100 ohms

d. around one megaohm

Solution:

87. Determine the force in Newton between 4 μC charges separated by 0.1 meter in air.

a. 1.44 N

b. 14.4 N

c. 144 N

d. 1440 N

Solution:

88. A crystal diode can be used as a rectifier because it offers _________.

a. low resistance in both directions

b. high resistance in one direction and low resistance in the other direction

c. high resistance in both directions

d. none of these

Solution:

89. Material usually used as gate of MOS for IC.

a. monocrystalline silicon

b. gold

c. polysilicon

d. platinum

Solution:

90. When a charge builds up without a flow of current, the charge is said to be:

a. ionizing

b. atomic

c. molecular

d. static

Solution:

91. As the frequency of a wave gets lower, all other things being equal, the value of Xc for a capacitor

a. increases negatively

b. decrease negatively

c. does not change

d. depends on the current

Solution:

92. A triangular wave exhibits

a. an instantaneous rise and a defined decay

b. a defined rise and an instantaneous decay

c. a defined rise and a defined decay, and the two are equal.

d. an instantaneous rise and an instantaneous decay

Solution:

93. Determine the ampere-turns when a 10 V battery is connected across a solenoid having 100 turns and a resistance of 5 ohms.

a. 50 At

b. 100 At

c. 200 At

d. 1,000 At

Solution:

94. In the derivative error compression

a. damping decreases and settling time decreases

b. damping increases and settling time increases

c. damping decreases and settling time increases

d. damping increases and settling time decreases

Solution:

95. Joule / Coulomb is the unit of

a. Electric filed potential

b. Potential

c. Charge

d. none of these

Solution:

96. Two sine waves are in phase opposition. Wave X has a peak amplitude of 4 V and wave Y has a peak amplitude of 8 V. The resultant has a peak amplitude of:

a. 4 V, in phase with the composites

b. 4 V, out of phase with the composites

c. 4 V, in phase with wave X

d. 4 V, in phase with wave Y

Solution:

97. How will you handle unused inputs in a logic gate/logic IC?

a. leave them floating

b. pull them down

c. pull them up

d. pull them down or up, depending on circuit function

Solution:

98. A laminated iron core has reduced eddy current losses because

a. the laminations are stacked vertically

b. the laminations are insulated from each other

c. the magnetic flux is concentrated in the air gap of the core

d. more wire can be used with less dc resistance in the coil

Solution:

99. If a magnetic flux occurs across 100 turns at a rate of 2 Wb/sec. What is the induced voltage as per Faraday’s law?

a. 100 V

b. 200 V

c. 400 V

d. 800 V

Solution:

a. aqueous solution of graphite

b. sweep voltage

c. secondary emission electrons

d. none of these

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