Gibilisco QA

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ELECTRONICS ENGINEERING GIBILISCO

CHAPTER 1

The atomic number of an element is determined byAns: the number of protons

The atomic weight of an element is approximatelydetermined byAns: the number protons plus the number of

neutrons

Suppose there is an atom oxygen. Containing eightprotons and eight neutrons in the nucleus, and the twoneutrons are added to the nucleus. What is the resultingatomic weight?Ans: 18

An ionAns: can have either positive or negative charge

An isotopeAns: can have either positive or negative charge

A moleculeAns: can consist of a single atom of an element

In a compound,Ans: There must always be two or more elements

An electrical insulator can made a conductorAns: by ionizing it.

Of the following substances, the worst conductor isAns: air.

Of the following substances, the best conductor isAns: copper

Movement of holes in a semiconductorAns: results in a certain amount of electric current.

If a material has low resistance, thenAns: it is a good conductor.

A coulombAns: is an extremely large of charge carriers.

A stroke of lightningAns: is a discharge of static electricity.

The volt is the standard unit ofAns: electromotive force

If an EMF of 1 volt is placed across a resistance of 2ohms, then the current isAns: half an ampere

In a battery, chemical energy can sometimes bereplenished byAns: charging it.

A fluctuating magnetic fieldAns: produces a fluctuating electric field.

Visible light is converted into electricityAns: in a photovoltaic cell.

CHAPTER 2

A positive electric poleAns: has fewer electrons than the negative pole/

An EMF of 1 VAns: can sometimes produce a large current

A potentially lethal electric current is on the order ofAns: 0.1 A

A current of 25 A is most likely drawn byAns: a typical household

You are told that an air conditioner has cooled a roomby 500 BTU over a certain period of time. What is thisamount of energy in kWh?Ans: 0.147 kWh

Of the following energy units, the most often used todefine electrical energy isAns: the kilowatt-hour

The frequency of common household ac in the UnitedStates isAns: 60 Hz

Half-wave rectification means thatAns: half of the ac wave is cut-off.

In the output of a half-wave rectifier,Ans: the effective voltage is less than that of the ac

input wave.

In the output of a full wave rectifier,Ans: the effective voltage is the same as that of theac input wave.

A low voltage, such as 12 V,Ans: can be dangerous under certain conditions.

Which of the following units can representmagnetomotive force?Ans: The ampere-turn

Which of the foloowing units can represent magneticflux density?Ans: the gauss.

A ferromagnetic materialAns: concentrates magnetic flux lines within itself.

CHAPTER 3

The attraction or repulsion between two electricallycharged object is calledAns: Electrostatic force


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The change in the direction of a compass needle, whencurrent carrying wire is brought near, is calledAns: Electromagnetic deflection

Suppose a certain current in a galvanometer causes theneedle to deflect by 20 degrees, and then this current isdoubled while the polarity stays the same. The angle ofthe deflection willAns: increase.

One important advantage of an electrostatic meter isthe fact thatAns: it can detect and indicate ac voltages as well

as dc voltages.

A thermocoupleAns: gets warm when dc flows though it.

An important advantage of an electromagnet type meterover a permanent magnet meter is the fact thatAns: the electromagnet meter gets more rugged.

Ammeter shunts are useful because

Ans: they allow for measurements of large currents.

Voltmeters should haveAns: high internal resistance.

In order to measure the power-supply voltage that isapplied to an electrical circuit, a voltmeter should beplacedAns: in parallel with the circuit that works from the

supply.

Which of the following will not normally cause a largeerror in an ohmmeter reading?Ans: A small change in the resistance to be

measured.

The main advantage of FETVM over a conventionalvoltmeter is the fact that the FETVMAns: draws less current from the circuit under test.

Which of the following is not a function of a fuse?Ans: To ensure there is enough current available for

an appliance to work right.

The utilitys motor speed depends dir ectly onAns: the number of watt-hours being used at the

time.

A utility meters readout indicates Ans: energy.

A typical frequency counterAns: is accurate to six digits or more.

A VU meter is never used to get a general indication ofAns: visible light intensity.

The meter movement in an illumination meter directlymeasuresAns: current.

An oscilloscope cannot be used to indicateAns: Energy

CHAPTER 4

Suppose you double the voltage in a somple dc circuit,and cut the resistance in half. The current willAns: becomes four times as great.

You can expect to find a wiring diagramAns: in the service/repair manual for a two-way

radio.

Suppose you have an unlimited supply of 1-W, 100- resistors. You need to get a 100- , 10 -W resistor. Thiscan be done most cheaply by means of a series-parallelmatrix ofAns: 4x4 resistors.

Suppose you have an unlimited supply of 1-W, 1000- resistors and you need a 500- resistance rated at 7 Wor more. This can be done by assembling

Ans: four sets of resitors in series, and connectingthese four sets in parallel.

Suppose you have an unlimited supply of 1-W, 1000- resistors and you need to get a 3000- , 5 -W resistance.The best way is toAns: do something other than any of the above

Good engineering practice usually requires that aseries-parallel resistive network be assembledAns: form resistors that are all identical.

CHAPTER 5

In a series-connected string of ornament bulbs, if onebulb gets shorted out, which of the following will occur?Ans: The current in the string will go up.

Fill in the blank in the following sentence to make it true:In a series or parallel dc circuit sum of the ___s in eachcomponent is equal to the ___ provided by the powersupply. Ans: wattage

In a voltage divider network, the total resistanceAns: should be as small as the power supply will

allow.

The maximum voltage output from a voltage dividerAns: is equal to the supply voltage.

CHAPTER 6

Proper biasing in an amplifier circuitAns: can be obtained using a voltage divider

network.


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A transistor can be protected from needless overheatingbyAns: a current limiting resistor.

A bleeder resistorAns: is connected across the capacitor in a power

supply.

Carbon composition resitorsAns: have essentially no capacitance or inductance.

A logical place for a wirewound resistorAns: in a high power dc circuit.

A metal film resistorAns: does not have much inductance.

What type of resistor, or combination of resistors, wouldyou use as the meter-sensitivity control in a testinstrument, when continuous adjustment is desired?Ans: A linear taper potentiometer.

What type of resistor, or combination of resistors, would

you use as the volume control in a stereo compact-disc(CD) player?Ans: An audio taper potentiometer.

An advantage of rheostat over a potentiometer is thefact thatAns: a rheostat can handle more current.

A resistor has a value of 680 , and you expect that itwill have to draw 1 mA maximum continuous current ina circuit youre building. What power rating is good forthis application, but not needlessly high?Ans: W

Suppose a 1 k resistor will dissipate 1.05 W, and you

have a good supply of 1 W resistors of various ohmicvalues. If there s room for 20 percent resistance error,the cheapest solution is to useAns: a pair of 2.2 k , 1-W resistors in parallel.

CHAPTER 7

The chemical energy in a battery or cellAns: changes to electrical energy when the cell is

used.

A cell cannot be recharged is known asAns: a primary cell.

A Weston cell is generally usedAns: as a voltage reference source.

The voltage produced by a battery of multiple cellsconnected in series isAns: more than the voltage produced by a cell of

the same composition.

A direct short-circuit of a large battery can causeAns: a physical rupture or explosion.

Alkaline cellsAns: generally work better in radios than zinc-

carbon cells.

The energy in a cell or battery depends mainly onAns: its physical size.

In which of the following devices would a lantern batterymost likely be found?Ans: a two-way portable radio.

In which of the following devices would a transistorbattery be the best power choice?Ans: an electronic calculator

For which of the following applications would youchoose a lithium battery?Ans: A microcomputer memory backup.

Where would you most likely find a lead-acid battery?Ans: In an uninterruptible power supply.

A cell or battery that maintains a constant current-

delivering capability almost until it dies is said to haveAns: A flat discharge curve.

Where might you find a nickel-based battery?Ans: More than one of the above.

A disadvantage of mercury cells and batteries is the factthatAns: mercury is destructive to the environment.

What kind of battery should never be used until it dies?Ans: Nickel based.

The useful current that is delivered by a solar powersystem

Ans: connecting two or more groups of solar cellsin parallel.

An interactive solar power systemAns: allows a homeowner to sell power to the

electric company.

An advantage of methanol over hydrogen for use in fuelcells is the fact thatAns: methanol is easier to transport and store.

CHAPTER 8

The geomagnetic fieldAns: makes a compass work.

Geomagnetic lines of fluxAns: are horizontal at the geomagnetic equator.

A material that can be permanently magnetized isgenerally said to beAns: ferromagnetic.

The force between a magnet and a piece offerromagnetic metal that has not been magnetizedAns: is never be repulsive.


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The presence of a magnetic field can always beattributed toAns: motion of electric charge carriers.

Lines of magnetic flux are said to origniateAns: at a north magnetic pole.

The magnetic flux around a straight, current-carryingwireAns: is strongest near the wire.

The gauss is a unit ofAns: magnetic flux density

A unit of overall magnetic field quantity is theAns: Maxwell.

Which of the following can occur during a geomagneticstorm?Ans: More than one above can occur.

An ac electromagnetAns: attracts pure, unmagnetized iron.

An advantage of an electromaganet over a permanentmagnet is a fact thatAns: an electromagnet can be switched on and off.

A substance with high retentivityAns: is well suited to making a permanent magnet.

Suppose a relay is connected into a circuit so that adevice gets a signal only when the relay coil carriescurrent. The relay isAns: normally open.

A device that repeatedly reverses the polarity of amagnetic field in order to keep a dc motor rotating is

known asAns: A commutator.

A high tape-recorder motor speed is generally used forAns: video recording and playback.

An advantage of a magnetic disk, compared withmagnetic tape, for data storage and retrieval is thatAns: data can be stored and retrieved more quickly

with disks than tapes.

A magnetic hard disk is usually part ofAns: A computer.

TEST: PART 1

An application in which an analog meter would almostalways be preferred over a digital meter isAns: the signal strength indicator in a radio

receiver.

Which of the following statement is false?Ans: The current in a dc circuit is divided up among

the resistances.

The ohm is a unit ofAns: opposition to electrical current.

A wiring diagram differs from a schematic diagram inthatAns: A wiring diagram shows the component

values, but a schematic diagram might not.

In which of the following places would you be mostlikely to find a wirewound resistor?Ans: A dc circuit location where a large amount of

power must be dissipated.

The number of protons in the nucleus of an element isknown as theAns: atomic number.

A hot wire ammeterAns: can measure ac as well as dc.

Which of the following units indicates at which energy isexpended?Ans: Watt

Which of the following states Ohms Law? Ans: Ohms equal volts divided by amperes.

The current flowing into a power in a dc circuit is equalto the currentAns: Flowing out of that point.

In a loudness meter in a hi-fi system is generallycalibrated inAns: Decibels.

An electrically charged atom (either positive ornegative) is known asAns: an ion.

The peak voltage in an ac wave is alwaysAns: is greater than or equal to the average voltage.

A primitive device for indicating the presence of anelectric current isAns: a galvanometer.

A disadvantage of mercury cells is the fact that theyAns: can adversely affect the environment when

discarded.

Which of the following is not a common use for aresistor or set of resistorsAns: Helping a capacitor to hold its charge for a

long time.

When an electrical charge exists but there is no flow ofcurrent, the charge is said to beAns: static.

The sum of the voltages, going around a dc circuit, butnot including the power supply, hasAns: an equal value, but the opposite polarity from,

the supply.


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A watt-hour meter measuresAns: Energy.

Every chemical element has its own unique type ofparticle, which is known as itsAns: Proton.

An advantage of magnetic disk over magnetic tape fordata storage is the fact thatAns: data storage and retrieval is faster on disk.

A sample of material with resistance so high that it canbe considered infinite for most practical purposes isknown asAns: an insulator.

Primary cellsAns: cannot be recharged.

A rheostatAns: can be used in high voltage and/or high powerdc circuits.

How much a typical dry cell provide?Ans: 1.5 V.

A geomagnetic stormAns: can disturb the earths magnetic field.

The advantage of an alkaline cell over a carbon zinc cellis the fact thatAns: the alkaline cell can deliver useful current atlow temperatures.

A unit of electrical charge quantity is theAns: Coulomb.

A unit of conductance is the

Ans: Siemens.

The main difference between a lantern battery and atransistor battery is the fact thatAns: A lantern battery has more energy stored in itthan a fresh transistor battery.

Nickel based batteries would most likely be foundAns: in handheld radio transceivers.

A voltmeter should haveAns: High internal resistance.

The purpose of a bleeder resistor is toAns: protect people against the danger of electricshock.

A dc electromagnetAns: has constant polarity.

The rate at which charged carriers flow is measured inAns: Amperes

A device commonly used for remote switching of high-current circuits isAns: A relay.

Memory in nickel-based cell or batteryAns: can usually be remedied by repeateddischarging and recharging.

A material with high permeabilityAns: concentrates the magnetic lines of flux.

A chemical compoundAns: consists of two or more atoms.

The main problem with bar-graph meters is the fact thatAns: they cannot give very precise readings.

CHAPTER 9

Which of the following can vary with ac, but never withdc?Ans: Frequency

The length of time between a point in one cycle and thesame point in the next cycle of an ac wave is theAns: Period

On a spectrum analyzer, an ac signal having only onefrequency component looks likeAns: A single pip.

The period of an ac wave, in seconds, isAns: equal to 1 divided by the frequency in Hertz

The 6 th harmonic of an ac wave whose period is 1.000millisecond (1.000 ms) has a frequency ofAns: 6.000 kHz

A degree of phase representsAns: 1/360 of a cycle

Suppose that two ac waves have the same frequencybut differ in phase by exactly 1/20 of a cycle. What isthe phase difference between these two waves?Ans: 180 degrees.

A triangular wave exhibitsAns: a defined rise and a defined decay, and thetwo are equal.

Three phase acAns: consists of three sine waves in differentphases.

If two perfect sine waves have the same frequency andthe same amplitude, but are in opposite phase, thecomposite waveAns: has zero amplitude (that is, it does noe exist),because the two input waves cancel each other out.

If two perfect sine waves have the same frequency andthe same phase. The composite waveAns: is a sine wave with an amplitude equal to thesum of the amplitudes of the two original waves.

In a perfect sine wave, the peak-to-peak amplitude isequal toAns: twice the peak amplitude


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Which one of the following does not affect the poweroutput available from a particular ac generator?Ans: The type of natural energy source used.

If a 175 V dc source were connected in series with theutility mains from a standard wall outlet, the result wouldbeAns: Fluctuating dc.

An advantage of ac over dc in utility applications is thefact thatAns: ac is easier to transform one voltage toanother.

CHAPTER 10

An inductor works byAns: storing energy as a magnetic field.

Which of the following does not affect inductance of anair-core coil, if all other factors are held constant?Ans: frequency

In a small inductanceAns: energy is stored and released quickly.

A ferromagnetic core is placed in an inductor mainly toAns: increase the inductance.

Inductors in series, assuming there is no mutualinductance, combineAns: like resistors in series.

With permeability tuning, moving the coil further into asolenoidal coilAns: increases the inductance.

A significant advantage in some situations of a toroidalcore over a solenoid is the fact thatAns: the magnetic flux in a toroid is practically allwithin the core.

A major feature of a pot core inductor isAns: large inductance in small volume.

As an inductor core material, airAns: has high permeability.

At a frequency of 400 Hz, which is in the AF range, themost likely form for an inductor would beAns: toroidal.

At a frequency of 95.7 MHz, which is in the frequency-modulation (FM) broadcast band and is considered partof the very high frequency (VHF) radio spectrum, agood form for an inductor would beAns: air-core.


CHAPTER 11

Capacitance acts to store electrical energy asAns: electric field.

As capacitor plate area increases, all other things beingequal,Ans: the capacitance increases.

As the spacing between plates in a capacitor is smaller,all other things being equal,Ans: the capacitance increases.

A material with a high dielectric constantAns: acts to increase capacitance per unit volume.

The main advantage of air as a dielectric material forcapacitors is the fact that itAns: has low loss.

Which of the following is not a characteristic of micacapacitors?Ans: Small size, even for large values of

capacitance.


Which of the following capacitance values is mosttypical of a disk-ceramic capacitor?Ans: 100 pF

Which of the following capacitance values is mosttypical of a paper capacitor?Ans: 0.01 uF

Which of the following capacitance values is mosttypical of an air-variable capacitor?

Ans: 1 to 100 pF Which of the following capacitors is polarized?

Ans: Electrolytic

If a capacitor has a negative temperature coefficient,thenAns: its capacitance decreases as the temperaturerises.

CHAPTER 12

Which of the following is not a general characteristic ofan ac wave?Ans: The electrons flow in the same direction.

All sine wavesAns: have similar general appearance.

The derivative of a sine waveAns: is the rate of change in the instantaneousvalue.

A phase difference of 180 in the circular motion modelof a sine wave representsAns: revolution


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You can add or subtract a certain number of degrees ofphase to or from a wave, and end up with exactly thesame wave again. This number isAns: 360, or any whole-number multiple of it.

You can add or subtract a certain number of degrees ofphase or to from a sine wave, and end up with aninverted (upside down) representation of the original.This number isAns: 180, or any odd-whole number multiple of it.

Suppose two waves are in phase coincidence. One haspeak values of 3 V and the other has peak values of 5 V. The resultant has voltages ofAns: 8 V pk, in phase with the composites.

As shown on a graph, shifting the phase of an ac sinewave by 90 is the same thing asAns: moving it right or left by cycle.

Two pure sine wave differ in phase by 180 can beconsidered toAns: be in phase opposition

Suppose two sine waves are in phase opposition. WaveX has a peak amplitude of 4 V and wave Y has a peakamplitude of 8 V. The resultant has voltages ofAns: 4 V pk, in phase with wave Y.

If wave X leads wave Y by 45, thenAns: Wave Y is 1/8 cycle behind wave X.

If wave X lags wave Y by 1/3 cycle, thenAns: WAye Y is 120 ahead of wave X.

In vector diagram, the length of the vector representsAns: the peak amplitude of a sine wave

In vector diagram, the angle between two vectorsrepresentsAns: the phase difference between two sine waves.

In vector diagrams, the distance from the center of thegraph representsAns: peak amplitude

In diagrams, the progression, of the is sometimesdepicted asAns: counterclockwise rotation of a vector

CHAPTER 13

As the number of turns in a coil that carries acincreases without limit, the current in the coil willAns: decrease, approaching zero

As the number of turns in a coil increases, thereactance at a constant frequencyAns: increases

As the frequency of an ac wave gets lower, the value ofxL for a particular coil of wireAns: decreases.

Each point in the RL plane.Ans: corresponds to a unique combination ofresistance and inductive reactance.

If the resistance R and the inductive reactance XL bothare allowed to vary from zero to unlimited values, butare always in the ratio 3:1, the points in the RL plane forall the resulting impedances will lie alongAns: a ray of indefinite length, pointing outward theorigin.

Each specific complex impedance value defined in theform R + jX L Ans: All of the above are true.

A vector is defined as mathematical quantity that hasAns: magnitude and direction

In a circuit containing inductive reactance but noresistance, the phase angle isAns: equal to 90.

If the inductive reactance and resistance in an RL circuit

are equal (as expressed in ohms) then what is thephase angle?Ans: 45

CHAPTER 14

As the size of the plates in a capacitor increases, allother things are being equalAns: the value of x C decreases negatively.

If the dielectric material between the plates of acapacitor is changed, all other things being equal.Ans: we cannot say what happens to x C withoutmore data.

As the frequency of a wave gets lower, all other thingsbeing equal, the value of x C for a capacitorAns: increases negatively.

Each point in the RC planeAns: corresponds to a unique combination ofresistance and reactance.

If R increases in an RC circuit, but the capacitance andthe frequency are nonzero and constant, then the vectorin the RC plane willAns: get longer and rotate counterclockwise.

Each complex impedance value R - jXCAns: represents a unique combination of resistanceand reactance.

In an RC circuit, as the ratio xC/R approaches zero, thephase angleAns: approaches 0.

In a purely resistive circuit, the phase angle isAns: 0

If xC/R = -1 then what is the phase angle?Ans: -45


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CHAPTER 15

The square of an imaginary numberAns: can never be positive

A complex numberAns: has a real number part and an imaginary part.

The complex impedance value 5 + j0 representsAns: a pure resistance

The complex impedance value 0 j22 representsAns: a pure capacitance

If the center conductor of a coaxial cable is made tohave a smaller diameter, all other things being equal,what will happen to the Zo of the transmission line?Ans: It will increase,

Susceptance and conductance add to formAns: Complex admittance

Absolute value impedance is equal to the square root of

which of the following?Ans: R 2 + X 2

Inductive susceptance is defined inAns: imaginary siemens

Capacitive susceptance values can be defined byAns: positive imaginary numbers

Which of the following is false?Ans: Characteristic impedance is complex.

In general, as the absolute value of the impedance in acircuit increasesAns: the flow of ac decreases

CHAPTER 16

When R = 0 in a series RLC circuit, but the netreactance is not zero, the impedance vectorAns: none of the above is correct

What will happen to the susceptance of a capacitor ifthe frequency is doubled and all other factors remainconstant?Ans: It will double

A vector pointing southeast in the GB plane wouldindicateAns: conductance and inductive susceptance

CHAPTER 17

The power in a pure reactance isAns: imaginary.

Which of the following is not an example of true power?Ans: The product of the rms ac through capacitorand the rms voltage across it.

Power factor is equal toAns: true power divided by apparent power.

The phase angle in an ac circuit is equal toAns: arctan (R/Z)

Which of the following should be minimized in an RFtransmission line?Ans: The line loss

Which of the following does not increase the loss in thetransmission line?Ans: Reducing the power output of the source.

Which of the following is a significant problem thatstanding waves can cause in an RF transmission line?Ans: All of the above

CHAPTER 18

In a step-up transformer,Ans: the primary voltage is less than the secondary

voltage.

The capacitance between the primary and thesecondary windings of a transformer can be minimizedbyAns: placing the windings on opposite sides of atoroidal core.

A transformer has a secondary to primary turns ratio of0.167. This transformer isAns: a step down unit.

Which of the following statements is false, concerningair cores compared with ferromagnetic cores?Ans: Air concentrates the magnetic lines of flux

Eddy currents causeAns: an increase in core loss.

The shell method of transformer windingAns: provides maximum coupling

Which of these core types is best if you need a windinginductance of 1.5 H?Ans: Ferromagnetic pot core

An advantage of toroid core over a solenoid core is thefact thatAns: the toroid confines the magnetic flux

High voltage is used in long-distance powertransmission becauseAns: the I2R losses are minimized

In a household circuit, 234-V rms electricity usually hasAns: three phases.

In a transformer, a center tap often exists inAns: the secondary winding

An autotransformerAns: consists of a single tap winding


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If there is reactance in the load to which a transformer isconnected, thenAns: a perfect impedance match cannot beobtained.

TEST: PART 2

Mutual inductance causes the net value of a set of coilsAns: vary, depending on the extent and phase ofmutual coupling.

In a series RL circuit, as the resistance becomes smallcompared with the reactance, the angle of lagapproaches which of the following?Ans: 90

In a parallel configuration, susceptancesAns: simply add up.

If two sine waves are 180 out of phase, it represents adifference ofAns: of a cycle.

If R denotes resistance and Z denotes absolute-valueimpedance then R/Z represents theAns: power factor

Which of the following capacitor is polarized?Ans: Electrolytic

A coil with a toroidal, ferromagnetic coreAns: is essentially self shielding.

The efficiency of electric generatorAns: is equal to the electrical output power dividedby the mechanical input power.

Admittance isAns: a measure of the ease which a circuit passesac.

The absolute value of impedance Z of a parallel RLCcircuit, where R is the resistance and X is the netreactance, is found according to which of the followingformulas?Ans: Z 2 = R 2X2 /(R 2+X2)

Complex numbers are used to represent impedancebecauseAns: they provide a way to represent what happensin resistance-reactance circuits.

Which of the following (within reason) has no effect onthe value, in farads, of a capacitor?Ans: The frequency.

The 0 phase point in an ac sine wave is usuallyconsidered to be the point in time at which theinstantaneous amplitude isAns: zero and positive going.

The inductance of a coil can be adjusted in a practicalway byAns: varying the number of turns using multipletaps.

Power factor is defined as the ratio ofAns: true power to VA power.

The vector 40 + j30 in the RX plane representsAns: 40 of resistance and 30 of inductivereactance.

In a series RC circuit where R = 300 and xC = -30 ,Ans: the current leads the voltage by a few degrees.

In a step down transformer,Ans: the primary voltage is greater than thesecondary voltage.

A pure sine wave contains energy atAns: only one specific frequency.

Inductive susceptance is

Ans: negative imaginary

The rate of change (derivative)_ of a pure sine wave isanother pure sine wave that has the same frequency asthe original wave, andAns: leads the original wave by 90.

True power is equal toAns: the vector difference between VA and reactivepower.

The reactance of a section of transmission line dependson all of the following factors exceptAns: the current in the line.

When analyzing a parallel RLC circuit to find thecomplex impedance, you shouldAns: find the net conductance and susceptance,convert to resiatnce and reactance, and then addthese to get R + jX

Suppose that two pure sine waves have no dccomponents, have the same frequency, and have thesame peak-to-peak voltages, but they cancel each otherout when they combined. What is the phase differencebetween the waves?Ans: 180

The characteristic impedance of a transmission lineAns: depends on the construction of a line.

A capacitor with a negative temperature coefficientAns: exhibits increasing capacitance as thetemperature drops.


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CHAPTER 19

The term semiconductor arises fromAns: variable conductive properties of somematerials.

Which of the following is not an advantage ofsemiconductor devices over vacuum tubes?Ans: Ability to withstand high voltage spikes.

Of the following substances, which is the mostcommonly used semiconductor?Ans: Silicon

GaAs isAns: a compound

A disadvantage of MOS devices is the fact thatAns: they can be damaged by electrostaticdischarges.

Selenium works especially well inAns: photocells

Of the following, which material allows the lowestforward voltage drop in a diode?Ans: Germanium

A CMOS integrated circuitAns: requires very little power to function.

The purpose of doping is toAns: gives a semiconductor material specificproperties.

A semiconductor material is made into N typeAns: adding a donor impurity

Which of the following does not result from adding anacceptor impurity?Ans: The substance requires an electron surplus

In a P type material, electrons areAns: the minority carriers

Holes move fromAns: P-type to N-type material

When a P-N junction does not conduct even though avoltage is applied, the junction isAns: reverse biased at a voltage less than theavalanche voltage.

Holes flow the opposite way from electrons becauseAns: they have opposite electric charge

If an electron is considered to have a charge of -1 unit,then a hole can be considered to haveAns: a charge of + 1 unit

When a PN junction is forward biased, condiction willnot occur unlessAns: the applied volktage exceeds the forwardbreakover voltage.

If the reverse bias exceeds the avalanche voltage in aP-N junction,Ans: the junction will conduct current.

Avalanche voltage is routinely exceeded when a P-N junction acts as aAns: voltage regulator

Which of the following does not affect the junctioncapacitance of a diode?Ans: the phase of an applied ac signal

CHAPTER 20

When a diode is forward biased, the anode voltageAns: is positive relative to the cathode voltage

If a diode is connected in series with the secondarywinding of an ac transformer, and if the peak voltageacross the diode never exceeds the avalanche voltage,then the output of the complete transformer diode circuitis

Ans: none of the above

A crystal setAns: requires no battery

A diode detectorAns: is employed in some radio receivers

If the output wave in a circuit has the same shape asthe input wave, thenAns: the circuit is operating in a linear manner.

Suppose of the two input signal frequencies to a mixercircuit are 3.522 MHz and 3.977 MHz. At which of thefollowing frequencies can we expect a signal to exist atthe output?Ans: 455 kHz

Fill in the blanks to make the sentence correct: Aspectrum analyzer provides a display of ___ as afunction of ____.Ans: amplitude/frequency

Zener voltage is a specialized manifestation ofAns: avalanche voltage

The forward breakover voltage of a silicon diode isAns: about 0.6 V

A diode audio limiter circuitAns: can cause distortion under some conditions.

The capacitance of a varactor varies with theAns: reverse voltage

The purpose of the I layer in a PIN diode is toAns: minimize the junction capacitance

Which of these diode types can be used as the keyelement in the oscillator circuit of a microwave radiotransmitter?Ans: An IMPATT diode


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A Gunnplexer is often used as aAns: microwave communications device

The most likely place you would find an LED would beinAns: a digital frequency display

Coherent electromagnetic radiation is produced byAns: laser diode

Suppose you want a circuit to operate in a stablemanner when the load impedance varies. You mightconsider a coupling method that employsAns: an optoisolator

The electrical power that a solar panel can provideeither in direct sunlight depends on all of the followingfactors exceptAns: the ac voltage applied to the panel

Emission of energy in an IRED is caused byAns: changes in electron energy within atoms.

A photodiode, when not used as a photovoltaic cell, hasAns: reverse bias.

CHAPTER 21

The output of a rectifier circuit without a filterAns: pulsating dc

Which of the following components is not necessariltrequired in a power supply designed to produce 12-V dcoutput with 117-V rms ac input?Ans: All of the above (transformer, rectifier, andfilter)

Of the following appliances, which need the biggesttransformer?Ans: A television broadcast transmitter

An advantage of full-wave bridge rectification is the factthatAns: it uses the whole transformer secondary forthe entire ac input cycle.

In a power supply designed to provide high power atlow voltage, the best rectifier circuit would probably betheAns: full wave, center tap arrangement

The part of a power supply preceding the regulator isAns: the filter

If a half wave rectifier is used with 165 V pk ac input,the effective dc output voltage isAns: considerably less than 165 V.

If a full wave bridge circuit is used with a transformerwhose secondary provides 50 V rms, the peak voltagethat occurs across the diodes in the reverse direction isapproximatelyAns: 70 V pk

What is the principal disadvantage of a voltage-doublerpower supply circuit?Ans: Poor regulation under heavy loads.

Suppose a transformer secondary provides 10 V rms acto a voltage doubler circuit. What is the approximate dcoutput voltage with no load?Ans: 28 V

The ripple frequency from a full wave rectifier isAns: twice that from a half-wave circuit

Which of the following would make the best filter for apower supply?Ans: A capacitor in parallel and a choke in series.

If you need exceptionally good ripple filtering for apower supply, which of the following alternatives willyield the best results?Ans: Use two capacitor/choke filtering sections incascade.

Voltage regulation can be accomplished by a Zener

diode connected inAns: parallel with the filter output, reverse biased.

A current surge takes place when a power supply is firstturned on becauseAns: the filter capacitor(s) must be initially charged.

Transient suppression is of importance mainly becauseit minimizes the risk ofAns: diode failure

If a fuse blows, and it is replaced with one having alower current rating, there is a good chance thatAns: the fuse will blow out right away.

Suppose you set a fuse with nothing but a straight wireinside. You can assume that this fuseAns: is a quick break type.

In order to minimize the risk of diode destruction as aresult of surge current that can occur when a powersupply is first switched on, which of the followingtechniques can be useful?Ans: Connecting multiple diodes in parallel, withlow-value resistors in series with each diode.

To repair a damaged power supply with which you arenot completely familiar, you shouldAns: leave it alone and have a professional work onit.

CHAPTER 22

In a PNP circuit, the collectorAns: is negative with respect to the emitter.

In many cases, a PNP transistor can be replaced withan NPN device and the circuit will do the same thing,provided thatAns: the power supply or battery polarity isreversed.


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A bipolar transistor hasAns: three semiconductor layers.

In the dual-diode model of an NPN transistor, theemitter corresponds toAns: either of the diode cathodes.

The current through a transistors depends onAns: more than one of the above.

With no signal input, a bipolar transistor would have theleast Ic whenAns: The E-B junction is reverse biased.

When a transistor is conducting as much as it can, it issaid to beAns: in state of saturation.

Which of the operating point is best if a largeamplification factor is desired with a weak signal input?Ans: Point C

The forward breakover pojnt for the E-B junction is

nearest toAns: point B

Saturation is nearest toAns: point D

The greatest gain occurs atAns: point C

In a common emitter circuit, the gain bandwidth productisAns: the frequency at which the gain is 1.

The bipolar transistor configuration most often used formatching a high input impedance to a low output

impedance puts signal ground atAns: the collector

The output is in phase with the input inAns: more than one of the above.

The greatest possible amplification is obtained inAns: a common emitter circuit.

The input is applied to the collector inAns: none of the above.

The configuration noted for its stability in RF poweramplifiers is theAns: common base circuit.

In a common base circuit, the output is taken from theAns: collector.

Suppose that the input signal to a transistor amplifierresults in saturation during part of the cycle. ThisproducesAns: the greatest possible amplification.

Suppose that the gain of a transistor in a commonemitter circuit is 100 at a frequency of 1 kHz, and thegain is 70.7 at 335 kHz. The gain drops to 1 at 210MHz. the alpha cutoff frequency is Ans: 335 kHz

CHAPTER 23

The current through the channel of a JFET is directlyaffected by all of the following exceptAns: gate bias

In an N channel JFET, pinchoff occurs when the gatebias isAns: large and negative

The current consists mainly of holes when a JFETAns: has a P-type channel

A JFET might work better than a bipolar transistor inAns: a weak signal RF amplifier

In a P-channel JFET,Ans: the drain is negative relative to the source

A JFET is sometimes biased at or beyond pinchoff inAns: a power amplifier

The gate of a JFET exhibitsAns: high impedance

Which of the following conditions is not normallydesirable in a JFET?Ans: A forward biased PN junction.

When a JFET is pinched off,Ans: the value of dI D /dE G is zero with no signal

input. Transconductance is a ratio of

Ans: a change in drain current to a change in gatevoltage.

Characteristic curves for JFETs generally showAns: drain current as a function of drain voltage.

A disadvantage of MOS components is the fact thatAns: they can be easily damaged by staticelectricity.

The input impedance of a MOSFET isAns: extremely high.

A significant between MOSFETs and JFETs is the factthatAns: MOSFETs can handle a wider range of gatebias voltage.

The channel in a zero-biased JFET is normallyAns: in a conducting state.

When an enhancement mode MOSFET is at zero bias,Ans: the drain current fluctuates with no signal.


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An enhancement mode MOSFET can be recognized inschematic diagrams by the presence ofAns: a broken vertical line inside the circle.

In a source follower, which of the electrodes receivesthe input signal?Ans: The gate

Which of the following circuits produces an output signalwave that is 180 out of phase with the input signalwave?Ans: The common source circuit.

Which of the following circuits can produce the greatestgain (amplification factor)?Ans: The common source circuit

CHAPTER 24

The decibel is a unit ofAns: relative signal strength

An oscillator at RF amplifier requires the use ofAns: a stage with gain

Suppose a circuit is found to have a gain figure of 15dB. Which of the following statements is true?Ans: The input signal is stronger than the outputsignal.

In an oscillator circuit, the feedback should beAns: just enough to sustain oscillation.

A power gain of 44 dB is equivalent to which of thefollowing output/input power ratios?Ans: 25,000:1

An RF chokeAns: passes dc but blocks RF signals.

The optimum capacitance values in an amplifier circuitdepend onAns: the input signal frequency.

An oscillator might fail to start for any of the followingreasons, exceptAns: in-phase feedback.

In which of the following FET amplifier types does draincurrent flow for exactly 50 percent of the signal cycle?Ans: Class B

The frequency at which a quartz crystal oscillatorproduces energy is largely dependent onAns: the physical thickness of the quartz wafer.

What bipolar amplifier type has some distortion in thesignal wave, with collector during most, but not all, ofthe cycle?Ans: class AB2

An RF oscillator usuallyAns: has most or all of its energy at a singlefrequency.

A class C amplifier can be made linear byAns: no means; a class C amplifier is alwaysnonlinear.

A frequency synthesizer hasAns: exceptional stability

A graphic equalizer is a form ofAns: tone control that can be used in an audioamplifier.

If the impedance of the load connected to the output ofan oscillator is extremely high,Ans: it is no cause for concern; in fact, it is a goodthing.

Suppose a certain bipolar-transistor PA is 66 percentefficient. The output power is 33 W. the dc collectorpower input is

Ans: 50 W

The arrangement in the block diagram representsAns: a waveform analyzer

A tuned RF PA must always beAns: adjusted for maximum power output.

Class B amplification can be used to obtain lowdistortion for audio applicationsAns: by connecting two identical bipolar transistorsor FETs, biased exactly at cutoff or pinchoff, in apush-pull configuration.

CHAPTER 25

A radio wave has a frequency of 1.55 MHz. The highestmodulating frequency can be used effectively isAns: 155 kHz

The reflected waveAns: arrives in a variable phase compared with thedirect wave.

An advantage of FSK over on/off keying is the fact thatAns: reduces the number of receiving errors.

The highest layer of the ionosphere isAns: F layer

An LSB suppressed carrier signal can be demodulatedbyAns: a product detector.

Which of the following modes is used to send imagedata over telephone lines?Ans: Fax

The S/N is a measure ofAns: the sensitivity of a receiver.


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Suppose an SSB suppressed carrier is at 14.335 MHz,and audio data is contained in a band from 14.335 to13.338 MHz. What is this mode?Ans: USB

A receiver that responds to a desired signal, but not toanother signal very close by in frequency, has goodAns: selectivity.

Fill in the blank in the following sentence to make it true:The deviation of a n arrowband voice FM signalnormally extends up to ____ either side of theunmodulated-carrier frequency.Ans: 5 kHz

An FM detector with built-in limiting isAns: a ratio detector

A continuously variable signal (Such as music audio)can be recovered from a signal having only a fewdiscrete levels or states by means ofAns: a D/A converter.

In which mode are signals interwined in the time domainat the transmitter, and then separated again at thereceiver?Ans: None of the above.

Which of the following modes can be demodulated byan enevelope detector?Ans: AM

The bandwidth of a fax signal is kept narrow byAns: sending the data at a slow rate of speed.

The dynamic range in a superhet is largely influencedby the performance of theAns: front end.

Frequency sweeping can be used to get a transmitter toproduceAns: spread-spectrum signals.

Fill in the blank to make the sentence true: Thereception of ____ can be improved by the use of DSP. Ans: any of the above (SSB signals, SSTV signals,synchronized communications signals)

CHAPTER 26

Suppose inverters are placed in series with both inputsof an AND gate. Under what conditions is the output ofthe resulting black box high?Ans: If and only if both inverter inputs are low.

Suppose an AND gat is followed by an inverter. Underwhat conditions is the output of the resulting black boxis low?Ans: if and only if both inputs are high

In Boolean algebra, addition representsAns: the logical OR operation.

If the output to a logical inverter is low, it means that Ans: the single input is high

The output of an AND gate is high if and only ifAns: all inputs are high

De Mrogans Theorem states that, for all logicalstatements X and Y,Ans: (-X) + (-Y) is equivalent to (X*Y).

If you see a number represented by FF in thedocumentation of an electronic circuit or system, youcan be certain that the number isAns: radix 16

Which of the following codes is digital?Ans: Morse, Baudot and ASCII (all of the above).

Which of the following voltages coulde normallyrepresent a 1 in positive logic?Ans: +5 V

Which of the following voltages might normally

represent a 1 in negative logic?Ans: 0.0 V

Fill in the blank to make the following sentence true: ___ data transmission refers to digital bits sent along asingle line, one bit after another.Ans: Serial

The inputs of an R-S flip-flop are known asAns: reset and set.

When both inputs of an R-S flip-flop are zero,Ans: the outputs stay as they are.

The fifth digit from the right in a binary number carries

which decimal value?Ans: 16

What is the octal equivalent of binary 1010?Ans: 12

What is the largest possible radix 10 numberrepresented as a six-digit binary number?Ans: 63

If one of the inputs to a two-input NOR gate is high,what is the output state?Ans: Low

Suppose a logic circuit has four inputs W,X, Y, and Z.How many possible input combinations are there?Ans: 16

TEST 3

In a JFET, the control electrode is usually theAns: gate

A diode can be used as a frequency multiplier becauseof itsAns: nonlinearity.


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Which of the following is not a common form of datatransmission?Ans: Polarization modulation.

A very brief, high voltage spike on an ac power line iscalledAns: a transient.

Which of the following is not a characteristic of anoscillator?Ans: Negative feedback.

Which of the layer of the ionosphere exists at the lowestaltitude?Ans: D layer.

The beta of a bipolar transistor is another name for itsAns: current amplification factor.

In a schematic diagram, the symbol for a PNP bipolartransistor can be recognized byAns: an arrow inside the symbol circle, pointingfrom the emitter toward the base.

Fill in the blank in the following sentence to make it true: An oscillator, ____ is an expression of the extent towhich the circuit maintains constant signal frequencyoutput under variable operating conditions, and is alsoan expression of its overall reliability. Ans: stability.

A Zener diode would most likely be found inAns: the voltage regulator in a power supply.

When the bias in an FET stops the flow of current, thecondition is calledAns: pinchoff

The VA rating of a transformer is an expression ofAns: none of the above

In an N-type semiconductor, the minority carriers areAns: holes

A disadvantage of a full wave rectifier is the fact thatAns: the output waveform is harder to filter than isthe case with a full-wave rectifier.

A power gain of 30 dB is equivalent to whichamplification factorAns: 1000

If a listener is not expecting any change in the intensityof a signal or sound, the smallest change that can benoticed is approximately which of the following?Ans: 3 dB

A common base circuit is commonly employed asAns: an RF power amplifier

A semiconductor material especially noted for itsphotoconductivity, and which is often used in makingphotocells isAns: selenium.

Which type of PA circuit provides the highest efficiencywhen used with the appropriate amount of drivingpower?Ans: Class C

Baudot is a form ofAns: digital code.

The most stable type of oscillator isAns: a quartz crystal.

If the source-gate junction in an FET conducts,Ans: it is a sign of improper bias.

What is the radix of the octal number system?Ans: 2 3

Signal to noise ratio (S?N) is often specified whenstatingAns: the sensitivity of a receiver.

In a reverse biased semiconductor diode, the junctioncapacitance depends on the

Ans: the width of the depletion region.

A simple power supply filter can be built withAns: a capacitor in parallel with the dc output.

Which of the following bipolar transistor circuits can, intheory, provide the most amplification?Ans: Common Emitter.

The ratio of the difference in I C to the difference in I B that occurs when a small signal is applied to the base ofa bipolar transistor is called theAns: dynamic current amplification.

An example of a device that is commonly used as an

oscillator at microwave frequencies isAns: A Gunn diode.

In the operation of a PNP bipolar transistor, which of thefollowing is normal concerning the emitter and collectorvoltages?Ans: The collector is negative relative to the emitter.

What can be done to minimize the capacitance of the P-N junction in a semiconductor diode, thereby makingthe component effective as a high-speed RF switch?Ans: A layer of intrinsic semiconductor can beplaced between the P- and N-type material.

Which type of modulation consists of one voicesideband, with a suppressed carrier?Ans: LSB

In an AND gate, the output is highAns: only when all inputs are high.

A voltage controlled oscillator makes use ofAns: a varactor diode.

The best electrical ground for a power supply isobtained by


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Ans: ensuring that the ground wire from the powersupply is connected to the third wire hole in one ofthe utility outlets of a properly installed three-wireelectrical circuit.

In an exclusive OR circuit, the output is highAns: only when the inputs have opposite logicstates.

A ratio detector is a circuit for demodulating which of thefollowing?Ans: FM

Suppose there is a binary digital black box with twoinputs, called X and Y, and an output called Z. if X = 0and Y = 1, then Z = 0. In all other instances Z = 1.Which of the following logical expressions respresentsthe content of the black box?Ans: X + (-Y)

A method of modulation in which the strength of pulsesvariesAns: pulse amplitude modulation

Boolean algebra isAns: a useful toll in binary digital circuit design

A voltage doubler power supply is best use forAns: circuits that need high voltage but do not drawmuch current.

An optoisolator consists of anAns: LED and a photodiode.

When a semiconductor is reverse-biased with a largeenough voltage, it will conduct. This phenomenon isknown asAns: avalanche effect.

Synchronizing pulses in a conventional analog TVsignalAns: keep the image from tearing or rolling.

In an enhancement mode MOSFET,Ans: the channel does not conduct with zero gatebias.

In a step up transformer,Ans: the secondary voltage is more than theprimary voltage.

CHAPTER 27

Imagine a center fed, straight wire antenna in freespace, whose length can be varied at will. At which ofthe following lengths is the radiation resistance at thefeedpoint the highest?Ans:

In order to obtain reasonable efficiency with a /4vertical antenna mounted poorly conducting soil at afrequency of 10 MHz, it is necessary toAns: minimize the loss resistance by installingnumerous ground radials.

A driven element in a parasitic array isAns: connected to the feed line

In a zepp antenna, feed-line radiation can be minimizedbyAns: using the antenna only at frequencies whereits length is a whole number multiple of /2.

Consider a single turn, closed loop having acircumference of 95 ft. suppose this loop is circular liesentirely in a single plane, is fed with open wiretransmission line and an antenna tuner, and is operatedat 20 MHz. The maximum radiation and response forthis loop can be expected to occurAns: along a line perpendicular to the planecontaining the loop.

Suppose an antenna has a radiation resistance of 40 at 8.5 MHz. What is the efficiency of this system?Ans: Impossible to determine without moreinformation.

Suppose an antenna system has a radiation resistance

of 40 and a loss resistance of 10 . What is theefficiency of this system?Ans: 80 percent

The null in a loopstick antenna existsAns: in the line that coincides with the coil axis.

All elements are added to a properly designed Yagiantenna,Ans: the f/s ratio increases.

When the radiation resistance in an antenna systemrepresents most of the total system resistance,Ans: the system can be expected to have highefficiency.

What state of affairs is optimal in a waveguide?Ans: None of the above.

Consider a single turn, closed loop having acircumference of 65 ft. Suppose this loop is circular, liesentirely in a single plane, is fed with open-wiretransmission line and an antenna tuner, and is operatedat 75 MHz. The maximum radiation and response forthis loop can be expected to occurAns: in the plane containing the loop

In a parasitic array, a director is usuallyAns: tuned to a slightly higher frequency than thedriven element.

A J pole is a modified form ofAns: zepp antenna

Which of the following antenna types is well suited touse with parallel-wire transmission line?Ans: The folded dipole.

Which of the following antenna types is not designed fortransmitting at 10GHz?Ans: A zepp antenna


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A vertical antenna measuring /2 in height does notrequire a ground system with low resistance becauseAns: None of the above apply.

CHAPTER 28

Because of the small size of ICs compared withequivalent circuits made from discrete components,Ans: higher switching speeds are attainable.

Which of the following is not an advantage of ICs overdiscrete components?Ans: Lower gain.

In which of the following devices would never find an ICas the main component?Ans: The final amplifier in a large radio broadcasttransmitter.

Which, if any, of the following component types is notpractical for direct fabrication on a chip?Ans: All three (Resistors, Capacitors and Diodes) of

the above component types are practical for directfabrication on a chip.

An op amp circuit usually employs negative feedbackonAns: control the gain

Suppose a communications channel carries severalsignals once. Which type of IC might be used to singlesignals out of reception?Ans: A multiplexer/demultiplexer

Which type of IC is most commonly used to determinewhether two dc voltages are the same or different?Ans: A comparator.

Which type of digital IC is least susceptible to noise?Ans: Transistor-transistor logic

Which of the following is not a characteristic of CMOSchips?Ans: Ability to handle extremely high power.

An absolute limit to the component density that can beachieved in IC technology is determined byAns: the size of the semiconductor atoms.

With a ROM chip,Ans: it is easier to read data from the device that towrite data into it.

With a RAM chip,Ans: it is easy to read data from the device, and justas easy to write data into it.

Which type of IC must be physically removed from thecircuit to have its memory contents changed?Ans: EPROM chip

With respect to memory, which of the following termsmeans that the data contents vanish if power isremoved from a chip?Ans: Volatility

In terms of the maximum number of transistors on asingle chip, how many orders of magnitude larger isVLSI than MLSI?Ans: Four

Which of the following shows the input and output of adifferentiator of a circuit?Ans: A

Which of the following shows the input and output of anintegrator of a circuit?Ans: C

Flip-flops are used to store data inAns: none of the above

Capacitors are used to store data inAns: none of the above

The phase of a sine wave signal can be shifted 180 byAns: applying the signal to the inverting input of theop amp.

CHAPTER 29

A major difference between a triode tube and an N-channel FET is the fact thatAns: triodes need higher power-supply voltages.

The control grid of a vacuum tube is the electricalcounterpart of theAns: gate of an FET

In a tetrode tube, the charge carriers areAns: free electrons, which pass among theelectrodes.

Which factor is most significant in limiting the maximumfrequency at which a tube can operate?Ans: The capacitance among the electrodes.

In a tube with a directly heated cathode,Ans: the filament serves as the cathode.

In a tube with a cold cathodes,Ans: there is no filament.

A screen grid enhances tube operation byAns: minimizing the risk that a tube amplifier willbreak into oscillation.

A tube with three grids is called aAns: pentode.

A tube with four grids is called aAns: hexode.


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An advantage of grounded-grid RF power amplifier overa grounded-cathode RF power amplifier is the fact thatthe grounded grid circuitAns: is more stable

A heptode tube hasAns: one plate

The electron gun in a CRT is another name for itsAns: cathode

The electron beam in an electrostatic CRT is bent byAns: electric fields produced by chargedelectrodes.

A grounded grid RF power amplifierAns: requires more driving power, for a given RFpower output, than a grounded-cathode RF poweramplifier.

In a Klystron, the electron beam density varies as aresult ofAns: velocity modulation.

A vidicon camera tube is noted for itsAns: slow response to image movement in dimlight.

The plate in a tetrode tube is normally connected toAns: a positive dc power-supply voltage.

The screen grid in a tetrode tube is normally connectedtoAns: a positive dc power supply voltage.

Which of the following is most suitable for measuringthe intensity of dim light?Ans: A photomultiplier tube

In a dissector tube, the aperture size is directly relatedto theAns: image resolution

CHAPTER 30

Which of the following devices would most likely beused for adjusting the frequency setting of a digital radiotransmitter or receiver?Ans: An optical shaft encoder.

Collimator of IR rays can be done by means ofAns: an ordinary lens

A computer mapAns: can help a robot find its way around.

The distance of a target from a radar station is calledAns: the range.

Which of the following devices is best for use as anultrasonic pickup?Ans: A piezoelectric transducer.

What do LORAN and the GPS have in common?Ans: They both involve measurement of distancesto determine the location of a receiver

A bright spot close to, and directly to the left, the centerof a conventional radar display indicates the presenceof a targetAns: at close range, west of the observing station.

Which of the following system enables a vessel tonavigate entirely from its own frame of reference,without the need for any electronic devices external toitself?Ans: An epipolar navigation system.

Ultrasonic waves travel through a vacuumAns: Forget it! No form of acoustic wave can travelthrough a vacuum.

Which of the following devices or techniques makes useof artificially generated magnetic fields to facilitatelocation within a work environment?Ans: None of the above.

Which of the following is not an example of atransducer?Ans: All of the above (microphone, radio antennaand headet) are examples of transducers.

A foam like material, having a resistance that variesdepending on how much it is compressed, is known asAns: an elastomer.

A stepper motorAns: results applied torque when stopped withcurrent going through its coils.

A permanent magnet is a key component ofAns: a dynamic microphone.

An electric motor is an example ofAns: an electromechanical transducer.

A capacitive proximity sensor should not be expected todetect the presence ofAns: a steel post.

A well-designed photoelectric sensorAns: is not easily fooled by stray sources of light.

An acoustic transducer can translate an ac electricalsignal intoAns: sound or ultrasound.

Body capacitance can be a problem withAns: capacitive pressure sensors.

Which of the following devices can be used to limit thetorque or force applied by an electromechanical devicesuch as robot?Ans: back pressure sensor.


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CHAPTER 31

A young person can hear sounds at frequencies as highas approximately which of the following?Ans: 20 kHz

Electromagnetic interference to a hi-fi amplifier canoccur in the presence ofAns: a nearby radio broadcast station.

The midrange audio frequenciesAns: none of the above.

In the acoustical design of a room intended for a homeaudio system,Ans: reflection of sound waves from walls shouldbe minimized.

A change of + 10 dB in an audio signal representsAns: a tenfold increase in acoustic power.

What is the frequency of an acoustic disturbance whosewave length is 120 mm in air?

Ans: 2.79 kHz

What is the frequency of a sound wave that propagatesat a speed of 1100 ft/s?Ans: Forget it! The frequency of sound wave isindependent of the propagation speed.

The relative phase of two acoustic waves from thesame source at the same time, one wave direct and onewave reflected from a wall, can affectAns: the position of antinodes and nodes.

In an acoustic sound wave,Ans: all of the sound power is concentrated at thesingle frequency.

Vinyl disks areAns: susceptible to physical damage.

If an amplifier introduces severe distortion in thewaveforms of input signals, then that amplifier isAns: operating in a nonlinear function.

Suppose a 10-W amplifier is used with speakersdesigned for a 100-W amplifier. Which of the followingstatements is true?Ans: The speakers are capable of handling theamplifier output.

Which of the following frequencies cannot be receivedby an AM/FM tuner?Ans: 95.7 kHz

Which of the following statements about woofers istrue?Ans: They are specifically designed to reproducelow-frequency sounds.

Suppose you have an amateur radio station and itstransmitter causes EMI to your hi-fi system. Which ofthe following would almost certainly not help?

Ans: Build a new transmitter that works on thesame frequencies with the same power output asyour existing transmitter.

In an analog audio tape recorder/player, the recordingheadAns: converts sound waves to fluctuating electriccurrent.

A rack-mounted hi-fi systemAns: can save floor space.

An audio mixerAns: eliminates EMI problems in all but the worstcases.

Which of the following devices or circuits ordinarilyemploys D/A conversion?Ans: A portable CD player.

Which of the following is an advantage of digital audioover analog audio?Ans: Digital audio is compatible with vinyl disks

and old fashioned reel to reel and cassette tape, butanalog audio is not.

CHAPTER 32

A network that employs one central computer andmultiple personal computers is calledAns: client-server network.

In order for a receiver to render a digitally encryptedsignal intelligible, that receiver mustAns: have a decryption key.

Which of the following devices or systems is notwireless?Ans: A computer with a telephone modem.

Eavesdropping of a wireless linkAns: is difficult impossible to detect.

In the United States, a license is required forAns: transmitting on amateur radio frequencies.

In a LEO satellite system, the repeaters are locatedAns: in space.

In a geostationary satellite link, the repeater is locatedAns: over the equator.

The term shortwave, in reference to audio, refers tosignals having wavelengths of approximatelyAns: 10 m to 100 m.

Which of the following is illegal to do in the UnitedStates using a ham radio station?Ans: Advertise used cars for sale.

A file server isAns: a central computer in a local area network.


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A device consisting of a receiver and transmitter in thesame case or enclosure, and commonly used forwireless communications, is calledAns: a transceiver.

End-to-end encryption providesAns: a higher degree of security than wireless onlyencryption.

A LAN in which each computer has more or less equalstatus, and in which each computer mores its own data,is known as aAns: peer-to-peer LAN

With respect to security, the term mil spec refers toAns: the highest obtainable level of security.

A radio signal is considered to be in the shortwave bandif its frequency is which of the following:Ans: 5 MHz

In cellular network, the region covered by a single basestation is called a

Ans: cell.

An advantage of a conventional hard-wired telephoneover a cell phone is the fact that a hardwired phone setAns: affords better privacy.

An advantage of a cell phone over a hard-wired phoneis the fact that a cell phone setAns: offers better mobility.

In a two way communication systems with full duplex,Ans: either party can hear the other at all times.

An advantage of LRO satellite systems overgeostationary satellite is the fact that

Ans: the regions near the geographic poles arecovered by LEO satellite systems, but not bygeostationary satellite systems.

CHAPTER 33

One megabyte is the same amount of data asAns: 1024 KB

The Web should be expected to work fastest for a userin New York City atAns: 2:00 a.m. local time on a Tuesday.

The sharpness of the image on a computer display canbe specified in terms ofAns: dot pitch.

The term cylinder refers toAns: a set of tracks in a hard drive.

An example of a mass-storage device is aAns: hard drive

The character string [email protected] would most likely representAns: an e-mail address.

The megabit per second (Mbps) is a common unit thatexpressesAns: the speed of an internet connection

A platter isAns: a part of hard drive

Protocol ensures thatAns: computers exchange data.

A packet isAns: a piece of data sent over the Net.

The main microprocessor in a computer is locatedAns: on the motherboard.

Cross-referencing among Web pages is done withAns: hypertext links.

Web page addresses usually begin with the lettershttp, which signifies a form ofAns: protocol.

A telephone modem containsAns: A/D converter.

An advantage of a flatbed scanner over a feedthroughscanner is the fact thatAns: a flatbed scanner can be used to scanmagazines or books intact, but a feedthroughscanner cannot.

Which of the following types of external storage providethe fastest access time, provided no software conflictsoccur?Ans: A flash memory module.

Which of the following is a serial-access medium?

Ans: Magnetic tape.

Which of the following character strings represents theproper format for an e-mail address?Ans: none of the above.

Which of the following devices is best suited foranimated graphics work involving fast motion, such ashigh end gaming?Ans: A display that does not use interlacing.

A thermal printer might be an ideal choice forAns: a salesperson who is on the road.

CHAPTER 34

Android takes the form ofAns: the human body

According to Asimovs three laws, under whatcircumstances is it all right for a robot to injure a humanbeing?Ans: Under no circumstances.
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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An RF field strength meter can be used toAns: detect the presence of a wireless buggingsystem.

The extent to which a machine vision system candifferentiate between two objects that are close togetheris called theAns: optical resolution.

A robot car or truck can best keep itself traveling downa specific lane of traffic by means ofAns: edge detection.

A rule based system is also known asAns: an expert system.

Suppose you are using a battery powered, multichannelbaby monitor, and you hear one end of a two-way radioconversation on the receiver . You can check the babysroom, and it is quiet. How might this problem be solved?Ans: Switch the monitor to a different channel.

In robotics, the term manipulator refers to

Ans: a robot arm, and the device at its end (such asa gripper)

A device with an IR sensor can be used to detect thepresence ofAns: warm or hot objects.

Proximity sensing is most closely a kin toAns: range plotting.

A telechir is always used in conjunction with aspecialized system ofAns: remote control.

A limit to the distance over which telepresence is

practical is imposed byAns: the speed of EM wave propagation.

The ionization potential of the air can be determined inorder toAns: detect smoke.

Two-dimensional range plottingAns: takes place in a single geometric plane.

Spherical coordinates can uniquely define the positionof a point in up toAns: three dimensions.

The total number of ways in which a robot arm canmove is known asAns: degrees of freedom.

The region in space throughout which a robot arm canaccomplish tasks is called itsAns: work envelope.

A robot arm that moves along three independent axes,each of which is straight and perpendicular to the othertwo, employsAns: Cartesian coordinate geometry.

Fill in the blank to make the following sentence true: Acolor vision system can use three grayscale cameras,equipped with filters that pass ___ light.Ans: blue, red, and green.

A robot typically determines the steepness of a slope bymeans ofAns: a clinometer.

TEST 4

Which of the following tasks can a displacementtransducer perform?Ans: It can convert and electrical signal intomechanical rotation through a defined angle.

Which of the following is not an advantage of an IC,compared to a circuit built with discrete components(individual resistors, capacitors, inductors, diodes, andtransistors)?Ans: Unlimited power handling capacity.

Computer memory is typically measured inAns: kilobytes, megabytes, and gigabytes.

A mode of communications in which either party canhear while talking, thus allowing one party to instantlyinterrupt the other at any time, is calledAns: full duplex.

An FM stereo tuner generally covers a frequency rangeofAns: 88 MHz to 108 MHz.

The peak power output from a multicavity KlystronAns: can be much greater than the average poweroutput.

To which of the following does the term platter apply?Ans: An individual disk in a hard drive.

Why can signals in the so-called shortwave bandsometimes propagate for thousands of kilometerswithout the need for satellites, repeaters, or any otherinfrastructure?Ans: Because EM waves at these frequencies areoften returned to the earth by the ionosphere.

What is the purpose of the filament in a vacuum tube?Ans: It heats the cathode, thereby increasing theelectron emission.

Figure Test4-1 is a schematic diagram ofAns: An open loop op-amp circuit.

Suppose that in the circuit Fig. Test 4-1, a resistor isconnected between the output and the inverting input.What effect will this have?Ans: It will decrease the gain.

Which of the following is an example of series accessstorage medium for computer disk?Ans: A magnetic tape.


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Which of the following is an undesirable characteristic ofELF radiation?Ans: None of the above apply.

A zepp antenna m easuring /2 can be orientedvertically, and the feed line placed so it lies in the sameline as the radiating element. This antenna is known asAns: A J pole.

The GPS can be used to determine the position of apoint inAns: three dimensions

In a component type hi-fi system, the cables connectingthe various devices shouldAns: be shielded whenever practicable.

In a radar display, the azimuth of a target is equal orproportional toAns: the clockwise angle between a radial line fromthe center toward geographic north, and a radialline from the center through the blip representingthe target.

Which of the following is an example of wirelesstechnology?Ans: The Global Positioning System.

The smoke detector can function by sensing a changein theAns: ionization potential of the air.

Computer disk storage is typically measured inAns: kilobytes, megabytes and gigabytes.

Which of the following antennas would most likely beused in space communications?Ans: A helical antenna

The use of a cell phone may be prohibited in acommercial aircraft in flight becauseAns: it can interfere with flight instruments andcommunications.

The circuit in Fig. Test 4-2 would be a bad choice foruse as a medium power audio amplifier becauseAns: Hold it! The circuit in Fig Test 4-2 would be agood choice for use as a medium power audioamplifier.

In an electrostatic CRT, the electron beam can bediverted up and down byAns: charged plates that attract or repel movingelectrons.

A device that translates 500-Hz sound waves into ac bymeans of the interaction between a permanent magnetand a coil of wire is an example ofAns: a dynamic transducer.

Which of the following considerations is most importantin a hi-fi audio power amplifier?Ans: nulls in the response to signals coming fromthe north and south.

A loopstick antenna, oriented so its end point toward theeastern and western horizons , exhibitsAns: nulls in the response to signals coming fromthe east to west.

Fill in the blank to make the following sentence t rue: An ____ functions by sensing variations in the relativephase acoustic waves reflected from objects in theenvironment. Ans: ultrasonic motion detector

Which of the following is an advantage of a large LCDover a large CRT display?Ans: Lighter weight.

An op amp can produce or facilitateAns: a high signal gain over a wide range offrequencies.

Which of the following is an application of gas filledtube?Ans: Decorative lighting.

Which of the following is a characteristic of steppermotor?Ans: It rotates in defined increments, notcontinuously.

With respect to ICs, terms such as MSI, LSI, and VLSIdefine theAns: maximum number of transistors per chip.

In a tetrode vacuum tube amplifier, the screen gridAns: reduces the capacitance between the controlgrid and the plate

Fill in the blank in the following sentence to make it true:On the Web data is transmitted by means of a ___ thatallows the files on distant computers to appear as if theyare on your own computer.Ans: protocol.

A robot arm with articulated geomteryAns: has joints, similar to those in a human arm.

The instantaneous output voltage of a differentiator isproportional toAns: the rate at which the instantaneous inputvoltage changes.

What type of devices require particular care in handling,so they are no destroyed by electrostatic dischargescan build up on a technicians body? Ans: MOS components.

According to Isaac Asimovs rules for the behavior ofrobots, a robot must not injure, or allow the injury of anyhuman,Ans: under any circumstances.

Computer data speed is typically measured inAns: kilobits per second, megabits per second, andgigabits per second.


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a cold day, might fail to set off the alarm in the presenceof a real threat. Ans: IR radiation detector

Suppose that five resistors, each one having the sameohmic value as all the others, are connected in seriesand the entire combination is connected to a 12-Vbattery. How does the voltage across any one of theresistors compare with the battery voltage, assuming noother loads are connected to the circuit?Ans: The voltage across any one of the resistors is1/5 of the battery voltage.

When the carrier and one of the sidebands are removedfrom an amplitude modulated signal, the result isAns: a single sideband signal.

In log polar navigation, a computer converts a polarcoordinate image toAns: A rectangular coordinate image.

Which of the following functions (a), (b), (c), or (d), ifany. Is a semiconductor diode never used to perform?

Ans: A semiconductor diode can perform any of theabove functions (Rectification, Detection,Frequency Multiplication, and Signal Mixing)

The reactance of a fixed capacitor, assuming it has noleakage conductance (that is, it has a theoreticallyinfinite dc resistance),Ans: decreases negatively (approaches zero) as thefrequency increases.

A common collector transistor circuit is often usedAns: to match a high impedance to a lowimpedance.

The internal conductance (expressed in siemens) of anammeter is generallyAns: high.

A half0wire length of wire, fed at one end with a quarterwave section of parallel-wire transmission line, is knownasAns: a zeppelin antenna

A twin T oscillator is commonly used for generatingAns: AF signals.

Suppose that five resistors, each one having the sameohmic value as all the others, are connected in series,and the entire combination is connected to a 12 Vbattery. How does that current through any one of theresistors compare with the current drawn from the

battery?Ans: The current through any one of the resistors issame as the current drawn from the battery?

When a nonzero net reactance exists in an ac circuit,the volt-ampere (VA), power also known as theapparent power isAns: greater than the true power.

When an impurity, also called a dopant, is added to asemiconductor material, it can contain either an excessof electrons or a deficiency of electrons. A dopant withan excess of electrons, also known as a donor impurity,results in the production ofAns: an N-type semiconductor.

In Fig. Exam 2, suppose the value of the fixedcapacitor, C1, is 330 pF, and the range of the variablecapacitor C2, is 10 to 365 pF. What is the span ofcapacitance values (minimum to maximum) that can beobtained with this parallel combination with switch Seither open or closed, as desired?Ans: 10 to 695 pF, over a continuous range

In Fig. Exam 2, suppose the value of the fixedcapacitor, C1, is 220 pF, and the range of the variablecapacitor C2, is 10 to 100 pF. What is the span ofcapacitance values (minimum to maximum) that can beobtained with this parallel combination with switch Seither open or closed, as desired?Ans: 5 to 320 pF, but with a gap in the range

Which of the following units is most often used forspecifying data speed in digital communicationssystems? Ans: Megabits b\per second.

In the output of a dc power supply, voltage regulationcan be obtained byAns: connecting a Zener diode in parallel, payingattention to the polarity.

Imagine an inductor and resistor connected in series,such that the inductive reactance and the resistance areboth equal to 400 at a frequency of 100 MHz. Howare the instantaneous current and the instantaneousvoltage related?Ans: None of the above are true.

Imagine a string of 20 holiday lights, all connected inparallel and plugged into a 120 V rms ac wall outlet. Ifone of the bulbs is short-circuited, what will happen?Ans: The fuse or circuit breaker will blow, and all ofthe remaining 19 bulbs will go out.

Suppose a coil and capacitor are connected in series,with jXL= j40 and jXc = -j70, and the coil has an internalresistance of 10 . Suppose the frequency of operationis 12.5 MHz. this circuit will exhibit resonance atAns: some frequency above 12.5 MHz

Imagine a transmission line consisting of two wires,each having a diameter of exactly 1 mm, and uniformely

spaced exactly 10 mm apart with nothing but air as thedielectric between them. If the two wires are moved sothey are uniformely spaced exactly 50 mm apart, andthe dielectric between them is nothing but air, whathappens to the characteristic impedance?Ans: It increases.

In an FM signal, deviation isAns: the maximum extent to which theinstantaneous carrier frequency differs from theunmodulated carrier frequency.


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A typical angular speed for an old-fashoined vinyl diskin a hi-fi sound system isAns: 33 rpm

An autotransformer can be recognized by the fact that ithasAns: a single, tapped winding

One of the purposes of the suppressor grid in a pentodevacuum tube amplifier is toAns: repel secondary electrons emitted by the plate,which could cause the power supply to burn out.

Consider two sine waves having identical frequency.Suppose that one wave leads the other by exactly 1/20of a cycle. What is the phase difference between thetwo waves?Ans: 18

In a cellular communications system, a technology inwhich cell overlap, but signals do not interfere with eachother because every phone set is assigned a uniquesignal code is known as

Ans: code division multiple access.

A steady magnetic field can be produced byAns: any of the above.

In Fig. Exam-3, what type of component can the boxwith the query symbol (?) contain in order for the circuitto function as indicated?Ans: A diode.

In which of the following applications would you neverfind an op amp used as the main active circuitcomponent?Ans: A microwave oscillator

In a circuit containing conductance, inductivesusceptance, and capacitive susceptance, a conditionof resonance exists if and only ifAns: the inductive and capacitive susceptancescancel out.

Imagine a perfect square wave with no dc component.That means that the positive and negative portions haveequal amplitudes and equal durations. Suppose you aretold that the voltage is 10 V pk-pk. What is the averagevoltage?Ans: 0.00 V

Fill in the blank in the following statement to make ittru e: It takes a certain minimum ___ voltage, known asthe forward breakover voltage, for conduction to occur

through a P- N junction.Ans: forward bias.

Figure Exam 4 is a generic diagram of a device that canbe used to measureAns: dc resistance

The maximum gain obtainable with an amplifier thatemploys a given bipolar transistorAns: gradually decreases as the frequencyincreases.

A phase comparator would most likely be found inAns: A PLL frequency synthesizer

An atom with 7 protons and 5 electrons is an exampleofAns: a positive ion

Electrical energy can be derived from hydrogen on asmall scale in a device calledAns: a fuel cell

The output wave of a common gate amplifier circuit witha pure sine wave inputAns: is in phase with the input wave

Which of the following capacitors is polarized?Ans: Electrolytic

The maximum radiation and response from a full-waveloop antenna, assuming there are no nearby conductorsor obstructions to distort the pattern, occursAns: perpendicular to the plane of the loop.

Suppose that five resistors, each having a differentohmic value from any of the others, are connected inseries, and the entire combincation is connected to a12-V battery. How does the current through any of theone resitors compare with the current drawn from thebattery?Ans: The current through any of the one resistors isthe same as the current drawn from the battery.

Figure Exam 5 shows a generic circuit that can be usedfor broadband RF power amplification. What is wrongwith the circuit as shown?Ans: The +12 V power source should be replacedwith a -12 V power source.

Imagine a string of 20 holiday lights, all connected inparallel and plugged into a 120-V rms ac wall outlet. Ifone of the bulbs is unscrewed and removed from thecircuit, what will happen?Ans: The remaining 19 bulbs will continue to shineexactly as before no more or less brightly.

When a volatile RAM chip is used in a computer,Ans: the contents of the memory can be easilyoverwritten.

A nickel-cadmium (NICAD) battery should never bedischarged until it is totally dead becauseAns: the polarity of one or more cells may reverse,ruining the battery.

Which of the following is an advantage of a CRT displayover an LCD for a computing workstation?Ans: You can get a bigger screen for a lower price.

The gauss is a unit ofAns: magnetic flux density.

Imagine an inductor and resistor connected in series,such that the inductive reactance is 300 and theresistance is 500 at a particular frequency. If thefrequency is decreased, what happens to the relative


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phase of the instantaneous current and theinstantaneous voltage?Ans: They become more nearly in phase.

Imagine two sine waves, one with a frequency of 50.00Hz and the other with a frequency of 60.00 Hz. Thephase difference between these two waves isAns: not definable.

Consider a variable capacitor connected in parallel witha fixed toroidal inductor. Suppose a signal of constantfrequency is applied to the combination. If the

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