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Test answers for Circuit Design 2016

(122, CL) Last updated: January 22
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122 Answered Test Questions:

1. The numerical values of what circuit elements are typically represented using colored stripes?

Answers:

• capacitors

• resistors

• diodes

• inductors

2. True or False: A multiplexer has multiple outputs.

Answers:

• False

• True

3. True or False? Any phase delay between two analog signals is lost after both signals have been three-level Nyquist sampled.

Answers:

• True

• False

4. Which of these statements expresses De Morgan's theorem?

Answers:

• NOT (A AND B) = (NOT A) OR (NOT B)

• NOT (A AND B) = (NOT A) NOR (NOT B)

• NOT (A AND B) = (NOT A) AND (NOT B)

5. In a low-pass filter consisting of a resistor and a capacitor, how will the cut-off frequency change if the capacitance is increased?

Answers:

• The cut-off frequency is lower for larger capacitances.

• The cut-off frequency is independent of the amount of capacitance in the circuit.

• The cut-off frequency is higher for larger capacitances.

6. In a high-pass filter consisting of a resistor and a capacitor, how will the cut-off frequency change if the capacitance is increased?

Answers:

• The cut-off frequency is independent of the amount of capacitance in the circuit.

• The cut-off frequency is higher for larger capacitances.

• The cut-off frequency is lower for larger capacitances.

7. What is the term to describe a multivibrator circuit with two outputs, both of which are stable in time?

Answers:

• bistable

• monostable

• astable

• multistable

8. Which of these is an active electronic component?

Answers:

• LED

• capacitor

• inductor

• resistor

9. A high-voltage primary circuit is isolated with the use of an optocoupler on a secondary circuit.  Does the addition of the optocoupler add inductance to either circuit?

Answers:

• yes, to both the primary and seconday circuit

• yes, to the primary circuit

• yes, to the secondary circuit

• no, the optocoupler does not add inductance

10. Consider a switch on a high-voltage circuit that is unsafe to operate manually.  How might the switch be safely actuated?

Answers:

• by removing any ground connections on the high-voltage circuit

• by increasing the inductance in the high-voltage circuit

• by using a secondary, low-voltage relay circuit

• by inserting a fuse on the high-voltage circuit

11. To what does the "sample rate" of a signal refer?

Answers:

• the phase of the noise used for dithering

• the number of voltage levels used to sample the signal amplitude

• how often in time the signal is sampled

12. Which of these variable resistors is non-ohmic?

Answers:

• rheostat

• varistor

• potentiometer

13. Which model is generally used for transmission lines?

Answers:

• distributed element model

• lumped element model

14. Consider an npn and a pnp transistor connected in series between the positive and negative terminals of a voltage supply.  A signal is input to the base of each and output to ground from their collector-emitter connection.  What is the common name for this configuration?

Answers:

• a diode bridge

• a reverse-biased divider

• a push-pull follower

• a double-double amplifier

15. Which of these is used as a construction base for prototyping of a circuit?

Answers:

• PCB

• breadboard

• surface mount board

16. Which of these is NOT an electromechanical component?

Answers:

• relay

• piezoelectric crystal

• photodiode

17. A "Schmitt trigger" is a simple circuit that employs what distinctive element?

Answers:

• a current balance

• an off-center-fed dipole

• an operational amplifier

• a mechanical spring

18. How does the breakdown voltage of a dielectric depend upon its thickness?

Answers:

• a thin layer of dielectric has a higher breakdown voltage than a thicker layer of the same dielectric

• a thick layer of dielectric has a higher breakdown voltage than a thinner layer of the same dielectric

• the thickness of a dielectric does not affect its breakdown voltage

19. Which logic operation yield a high output for two high inputs?

Answers:

• NOR

• AND

• OR

• NAND

20. An audio tuning circuit is an application of a:

Answers:

• high-pass filter

• low-pass filter

• band pass filter

21. If in a circuit  the input voltage (Vin) is applied across the series impedances Z1 and Z2 and the output is taken across Z2, what is the output voltage (Vout) given by?

Answers:

• Z2 . Vin

• Z1 . Vin

• [Z2 / (Z1 + Z2)] . Vin

• [Z1 / (Z1 + Z2)] . Vin

22. True or False? Differential signalling can be employed in both analog circuits and digital circuits.

Answers:

• True

• False

23. On an alternating-current appliance with a three-prong plug, on which lead should the power switch be connected?

Answers:

• the hot lead

• the neutral lead

• the ground lead

24. Which of these is NOT a part of a regular DC power supply?

Answers:

• transformer

• differentiator

• regulator

• filter

25. Which of the following is a nonlinear circuit element?

Answers:

• transistor

• capacitor

• inductor

• resistor

26. True or False: Reactance is the opposition of a circuit element to a change of electric current or voltage.

Answers:

• True

• False

27. Of what safety device is this a description: A magnetic or thermal stage that engages an opening of the circuit above a critical value of current?

Answers:

• a two- to three- prong plug adaptor

• a circuit breaker

• a ground-fault interruptor

• a relay

28. Three-phase alternating-current power is typically distributed on how many independent conductors?

Answers:

• three

• six

• one

• two

29. Which of these is NOT a method used for electric circuit analysis?

Answers:

• Superposition

• Planar Method

• Mesh Analysis

• Nodal Analysis

30. If A = 1 and B = 1 then A XOR B =

Answers:

• 0

• 1

31. Which of the following circuit elements is NOT likely to be found in a 120 VAC to 12 VDC adapter?

Answers:

• capacitor

• diode

• transformer

• balun

32. True or False?  Lightbulb power ratings are only correct for the rated voltage.

Answers:

• True

• False

33. Which of these can function as an electromagnet?

Answers:

• solenoid

• memristor

• JFET

• RTD

34. A string of decorative holiday lights is lit except for two burnt-out bulbs.  Are the bulbs of the string wired in parallel or series with each other?

Answers:

• The lights must be wired in series with each other.

• The lights must be wired in parallel with each other.

35. How many diodes are required to build the bridge in a full-wave rectifier that does not employ a transformer?

Answers:

• one

• three

• four

• two

36. According to Kirchoff's voltage law, the sum of the EMFs in any closed loop is equal to:

Answers:

• one

• the resistance of that loop

• the sum of the potential drops in that loop

• two

37. Which of the following devices can replace a fuse in a circuit and perform the same safety function?

Answers:

• a dimmer switch

• a circuit breaker

• a three-prong plug

• a ground-fault interruptor

38. True or False: An op-amp configured as an inverting integrator can function as a low pass filter.

Answers:

• True

• False

39. What are the names of the three terminals on a BJT transistor?

Answers:

• positive, negative, zero

• increasing, decreasing, inverting

• base, collector, emitter

• bias, collector, ground

40. In an 8-bit encoding, how many different values can be represented?

Answers:

• 17

• 16

• 8

• 256

41. What kind of relationship is described for impedences Z1 through Zn in a circuit, by the following equation? Z(eq) = Z1 + Z2 + ??? + Zn

Answers:

• parallel

• series

42. A resistor is an element that obstructs the flow of current in a circuit in accordance with

Answers:

• Faraday's Law

• Gauss's Law

• Ohm's Law

• Lenz's Law

43. Which of these is a passive electronic component?

Answers:

• diode

• transistor

• op-amp

• capacitor

44. Which of these is generally used to measure electrical resistance?

Answers:

• Wheatstone Bridge

• Maxwell Bridge

• Diode Bridge

• Galvanometer

45. In which of the following configurations do the capacitor(s) have the smallest individual voltages?

Answers:

• two 100-nF capacitors connected in series to 10 V

• two 100-nF capacitors connected in parallel to 10 V

• one 100-nF capacitor connected to 10 V

46. What is the name for the configuration in which an operational amplifier (op-amp) has its output connected to the non-inverting input?

Answers:

• short circuit

• positive feedback

• negative feedback

• tank circuit

47. A type of logic gate with outputs high, low, and high impedance is called:

Answers:

• triplexer

• tri-state buffer

• three phase switch

• impedance logic

48. True or False? A Fourier-transform spectrometer is suscueptible to Gibbs ringing.

Answers:

• True

• False

49. What standard circuit network often manifests as a "trim" potentiometer?

Answers:

• a voltage divider

• a NAND gate

• an analog-to-digital converter

• a low-pass filter

50. Which of the following is a primary disadvantage of a vacuum-tube amplifier compared with a solid-state amplifier?

Answers:

• poor high-voltage linearity

• low charge-carrier density

• high heater current

• overload clipping

51. The typical schematic representation of a transistor carries what one-letter abbreviation?

Answers:

• Q

• L

• T

• R

52. What do you call a theoretical circuit used in analysis, that retains all of the electrical characteristics of a given circuit?

Answers:

• source circuit

• analytical model

• equivalent circuit

• linear circuit

53. A kilowatt-hour is a typical unit for what quantity?

Answers:

• capacitance

• energy

• time

• power

54. Which of the following is a primary disadvantage of a solid-state amplifier compared with a vacuum-tube amplifier?

Answers:

• large physical size

• poor tolerance for high -current and -voltage transients

• short operational lifetime under normal conditions

• high power consumption

55. How is the Nyquist rate for a signal related to the bandwidth of the signal?

Answers:

• the bandwidth and Nyquist rate of a signal are not related

• a wider bandwidth requires a higher Nyquist rate

• a narrower bandwidth requires a lower Nyquist rate

56. One 120-VAC circuit has two 60-W light bulbs in parallel and another 120-VAC circuit has a single 100-W bulb.  In which circuit is more power dissipated?

Answers:

• the two 60-W parallel bulbs

• both systems dissipate the same amount of power

• the single 100-W bulb

57. Which of these inductors exhibits more energy losses at higher frequencies?

Answers:

• air core inductor

• ferromagnetic core inductor

58. A JK flip-flop circuit can be assembled entirely from four of which type of digital gate?

Answers:

• NOR

• XOR

• AND

• NAND

59. True or False?  XOR and XNOR are both associative.

Answers:

• False

• True

60. What is the approximate impedance of a universal serial bus (USB) computer connection?

Answers:

• 0.6 Ohm

• 50 Ohm

• 377 Ohm

• 1 million Ohm

61. What standard logic operation is represented by a household "three-way switch" in which two different switches operate the same light fixture?

Answers:

• OR

• NAND

• AND

• XOR

62. What kind of feedback does a thermostat employ?

Answers:

• positive

• negative

63. In which equivalent circuit can you replace a linear two-terminal circuit by a current source and a parallel impedance?

Answers:

• Norton equivalent

• Thevnin equivalent

64. An electrical circuit that converts AC electrical power from a lower voltage to a higher DC voltage is called a:

Answers:

• voltage multiplier

• voltage divider

• power amplifier

65. Which of these uses high frequency transformers?

Answers:

• DC power supply

• AC power supply

• switched mode power supply

66. What is the function of a diode clamp?

Answers:

• to remove the internal resistance from an electrochemical cell

• to maintain the voltage of a signal between fixed bounds

• to alleviate the usual 0.6-Volt forward drop

• the maintain the position of a diode during soldering

67. To what do the "rails" of an operational amplifier refer?

Answers:

• the potentials of the positive and negative terminals of the power supply

• the potentials of the positive and negative inputs to the amplifier

• any inverted but otherwise unmodulated outputs

• the two rows of contact pins on the integrated-circuit module

68. Which of the following statements about phase-locked loops is NOT true?

Answers:

• they are digital, not analog devices

• they are used in the demodulation of FM signals

• they can only function with feedback

• they require the incorporation of an oscillator

69. What artifact results from a failure to low-pass filter a signal before analog-to-digital conversion?

Answers:

• ringing

• quantization

• aliasing

• dithering

70. In a series RLC circuit, a larger series resistance will result in a

Answers:

• lower Q factor

• higher Q factor

71. The time between the change in a gate's input to the corresponding change in its output is called:

Answers:

• delay period

• response period

• switching time

• propogation delay

72. How many diodes are required to a half-wave rectifier?

Answers:

• three

• one

• four

• two

73. What is the term to describe a multivibrator circuit with two outputs, one of which is stable in time?

Answers:

• astable

• monostable

• bistable

• multistable

74. The number of gate inputs that can be driven by a particular logic gate's output is called that gate's:

Answers:

• gain

• drive limit

• fanout limit

• switch logic

75. What does a Colpitts Oscillator use to produce an oscillating frequency?

Answers:

• resistors and capacitors

• resistors and transistors

• inductors and resistors

• inductors and capacitors

76. What is the name for the process of splitting a signal, inverting one of the two resulting signals, transmitting both signals, inverting one of the signals upon reception of both, then summing the two signals?

Answers:

• differential signalling

• forward error correction

• packet division

• twisted-pair signalling

77. In a differentiator circuit, the output is approximately:

Answers:

• inversely proportional to the rate of change of input

• inversely proportional to the magnitude of the input

• directly proportional to the magnitude of the input

• directly proportional to the rate of change of input

78. How many diodes are in the bridge of a three-phase rectifier?

Answers:

• one

• six

• three

• four

79. What is the term to describe a multivibrator circuit with two outputs, neither of which is stable in time?

Answers:

• multistable

• astable

• bistable

• monostable

80. Which power supply takes its power from more than one source?

Answers:

• UPS

• SMPS

81. Which of the following is a linear circuit element?

Answers:

• transistor

• diode

• inductor

• vacuum tube

82. One 50-Ohm resistor and two parallel 100-Ohm resistors have the same impedance.  In which system do the resistors have lower current when dissipating 1 kW?

Answers:

• the system with one 50-Ohm resistor

• both systems have the same current in every resistor

• the system with two 100-Ohm resistors

83. On a printed circuit board that supports several different inductors in different circuits, are there any constraints to the layout of the inductors?

Answers:

• No, there are no constraints to the layout of the inductors.

• Yes, the inductors must be oriented side-by-side and anti-parallel in order to avoid coupling.

• Yes, the inductors must be oriented at right angles in order to avoid coupling.

• Yes, the inductors must be oriented co-axially along a line in order to avoid coupling.

84. Which kind of filter is produced by placing an input voltage across the series combination of a capacitor and a resistor and using the voltage across the resistor as an output?

Answers:

• high-pass

• low-pass

• band-pass

85. The minimum root-mean-square magnitude of alternating currents that are likely to cause uncontrollable muscle contraction and heart fibrillation in a human are in what range?

Answers:

• 1 to 3 A

• 10 to 30 A

• 0.01 to 0.03 mA

• 10 to 30 mA

86. A milliAmpere-hour is a typical unit for what quantity?

Answers:

• time

• charge

• energy

• power

87. Consider a push-pull follower amplifier: an npn and a pnp transistor connected in series between the positive and negative terminals of a voltage supply to which signal is input to the base of each and output to ground from their collector-emitter connection. In which class is such an amplifier?

Answers:

• C

• D

• A

• B

88. A group of branches in a circuit forming a complete loop is called a

Answers:

• mesh

• looped network

• node

• closed branch

89. How many diodes are required to build a full-wave rectifier that employs a center-tapped transformer?

Answers:

• four

• three

• two

• one

90. True or False? The presence of the ground lead on a three-prong alternating-current appliance plug alleviates the need for a ground-fault interruptor.

Answers:

• False

• True

91. On a printed circuit board, what is a flux capacitor?

Answers:

• an exploitation of the capacitance that is due to the lateral electric flux between two adjacent printed conductors

• a capacitor soldered on the underside of the board, without the benefit of pre-treatment with flux

• a capacitor with three connections: hot, neutral, and ground

• a high-power capacitor that is typically the first on the line after the power supply

92. What is the chacteristic feature of heterodyne processing compared with homodyne processing?

Answers:

• only heterodyne processing employs impedance matching

• only heterodyne processing employs square-law detection

• only heterodyne processing employs multiple signal paths

• only heterodyne processing employs frequency conversion

93. For which values of inputs A and B would a NAND gate and an XOR gate NOT have the same output?

Answers:

• A=1, B=1

• A=1, B=0

• A=0, B=1

• A=0, B=0

94. Which of the following combinations of gates could be used to realize the XOR function?

Answers:

• one AND, one NAND, and one OR

• two inverters and two ANDs

• three NANDs

• two ORs

95. Consider a typical household AC circuit that is protected by both a circuit breaker and a ground-fault interruptor.  A person accidentally shorts the hot lead to ground, drawing a lethal current of 100 mA.  Which of the two safety devices will trip?

Answers:

• Only the circuit breaker will trip.

• Only the ground-fault interruptor will trip.

• Both the ground-fault interruptor and the circuit breaker will trip.

• Neither the ground-fault interruptor nor the circuit breaker will trip.

96. Of what safety device is this a description: A primary circuit that is magnetically coupled to a secondary circuit in which imbalance of hot and neutral current is measured?

Answers:

• a fuse

• a circuit breaker

• a ground-fault interruptor

• a two- to three- prong plug adaptor

97. For inputs A = 1 and B = 1, which of these logic operations between A and B will yield output 1?

Answers:

• XOR

• XNOR

• NAND

• NOR

98. Two cross-coupled (the output of one gate serves as one of the other gate's inputs) NOR gates constitutes what type of digital circuit?

Answers:

• a NAND gate

• an SR latch

• an XNOR gate

• a JK flip-flop

99. The self-induced back voltage in a circuit that occurs when an inductive DC circuit is opened may be safely routed away from the switch with a diode connected across the inductor and against the DC voltage.  What is the main disadvantage of this practice?

Answers:

• the large inherent capacitance of the diode interferes with the DC operation

• the diode intermittenly conducts while the switch is closed, causing interference

• the large inherent inductance of the diode results in coupling to the inductor like a transformer

• the decay of the current in the inductor is relatively slow

100. What is the typical low-voltage cutoff for a "high" signal in transistor-transistor logic (TTL)?

Answers:

• 0.4 V

• 0.8 V

• 2.4 V

• 4.6 V

101. Why does an "L pad" impedance-matching network bear that name?

Answers:

• Because the network employs one or more inductors, elements that are traditionally abbreviated with the symbol "L."

• Because it was named in honor of Hendrik Lorentz, an early electromagnetic theorist.

• Because the two resistors in the network are traditionally oriented in the shape of the capital letter "L" on schematic drawings.

• Because it is similar to a launch pad in terms of the large amount of power throughput enabled by a favorable impedance match.

102. To which of the inputs will the feedback be routed for an operational amplifier (op-amp) employed as a non-inverting amplifier?

Answers:

• the inverting input

• the positive power supply

• the negative power supply

• the non-inverting input

103. Of the following four types of digital latches, which one can be configured (with cross-couplings) to operate as the other three?

Answers:

• a JK flip-flop can operate as a set-reset latch, a data flip-flop, and a toggle flip-flop

• a set-reset latch can operate as a JK flip-flop, a data flip-flop, and a toggle flip-flop

• a toggle flip-flop can operate as a set-reset latch, a data flip-flop, and a JK flip-flop

• a data flip-flop can operate as a set-reset latch, a JK flip-flop, and a toggle flip-flop

104. A "bias tee" consists of a single output that is capacitively coupled to a radiofrequency signal and inductively coupled to a DC signal.  What is the primary purpose of this device?

Answers:

• to demodulate the RF signal

• to match the impedance of the input and output

• to add a DC offset to an RF signal

• to remove a DC offset from an RF signal

105. Which model makes the simplifying assumption that all components in a circuit are ideal and all wires conduct perfectly?

Answers:

• lumped element model

• Maxwell's model

• differential model

• finite element model

106. In a high-pass filter consisting of a resistor and an inductor, how will the cut-off frequency change if the inductance is increased?

Answers:

• The cut-off frequency is independent of the amount of inductance in the circuit.

• The cut-off frequency is higher for larger inductances.

• The cut-off frequency is lower for larger inductances.

107. True or False: The lumped element model is used whenever the circuit's length is greater than the circuit's operating wavelength.

Answers:

• False

• True

108. In a system with a transmission multiplexer and a reception demultiplexer, how many outputs is it typical for the multiplxer to possess?

Answers:

• 0

• 4

• 1

• 32

109. A high-voltage primary circuit is isolated with the use of a relay switch on a secondary circuit.  Does the addition of the relay circuit add inductance to either circuit?

Answers:

• no, the relay switch does not add inductance

• yes, to the secondary circuit

• yes, to the primary circuit

• yes, to both the primary and seconday circuit

110. Dithering of an audiofrequency signal typically occurs at what stage?

Answers:

• in lieu of filtering prior to analog-to-digital conversion

• following digital-to-analog conversion and prior to playback

• following filtering and prior to analog-to-digital conversion

• prior to both filtering and analog-to-digital conversion

111. Dithering of a digital signal is a common method for combating what underisable phenomenon?

Answers:

• clipping

• race conditions

• edge ringing

• aliasing

112. What is the term for the amount by which a signal exceeds the minimum amount for a circuit's proper operation?

Answers:

• signal to noise ratio

• degradation ratio

• noise margin

• signal integrity

113. A transformer in which the windings are surrounded by the core is called

Answers:

• step up

• toroidal

• core form

• shell form

114. What is Wein Bridge used for?

Answers:

• measurement of capacitance

• full wave rectification

• measurement of inductance

• half wave rectification

115. True or False? The neutral lead of a polarized alternating-current plug is suitable for use as a chassis ground.

Answers:

• False

• True

116. True or False? Race conditions can only occur in digital circuits.

Answers:

• True

• False

117. Which of the following statements can be made concerning A XNOR (B XNOR C) = (A XNOR B) XNOR C ?

Answers:

• this is not true because XNOR is not commutative

• this is not true because XNOR is not associative

• this is true because XNOR is associative

• this is true because XNOR is commutative

118. In the coil stage prior to rectification, an automobile alternator typically generates which type of electricity?

Answers:

• split-phase alternating current

• direct current

• single-phase alternating current

• three-phase alternating current

119. Which of these is the equivalent of a farad, the unit of capacitance?

Answers:

• second/ohm

• joule/ampere

• ampere.second

• coulomb.volt

120. Digital latches may be constructed by cross-coupling (the output of one gate serves as one of the other gate's inputs) two of the same gates.  What configuration is equivalent to an SR NOR latch for which the two inputs act as Set and Reset?

Answers:

• a JK flip-flop

• a NOT-S, NOT-R NAND latch

• an SR NAND latch

• a NOT-S, NOT-R NOR latch

121. A differential amplifier made to produce two outputs of equal amplitude but opposite polarity is called

Answers:

• phase splitter

• inverting amplifier

122. In a low-noise block downconverter (LNB), at what frequency is the amplification typically executed?

Answers:

• at the sky frequency

• at the baseband frequency

• at the intermediate frequency