Gibilisco chapter 1

7/28/2019 Gibilisco chapter 1

1/100

The atomic number of an element is

determined by

a. the number of neutrons

b. the number of protons

c. the number of neutrons plus the

number of protons

d. the number of electrons


2/100

The atomic weight of an element is

approximately determined by

a. the number of neutrons

b. the number of protons

c. the number of neutrons plus the

number of protons

d. the number of electrons


3/100

Suppose there is an atom of oxygen eight

protons and eight neutrons in thenucleus, and two neutrons added to the

nucleus. What is the resulting atomic

weight?

a. 8

b. 10

c. 16d. 18


4/100

An ion

a. is electrically neutral.

b. has positive electric charge.

c. has negative electric charge.

d. can have either a positive or negative

charge.


5/100

An isotope

a. is electrically neutral.

b. has positive electric charge.

c. has negative electric charge.

d. can have either a positive or negative

charge.


6/100

A molecule

a. can consists of a single atom of an

element.

b. always contains two or more elements.

c. always has two or more atoms.

d. is always electrically charged.


7/100

In a compound,

a. there can be a single atom of an

element.

b. there must always be two or more

elements.

c. the atoms are mixed in which each

other but not joined.

d. there is always a shortage ofelectrons.


8/100

An electrical insulator can be made a

conductor

a. by heating it.

b. by cooling it.

c. by ionizing it.

d. by oxidizing it.


9/100

Of the following substances, the worst

conductor is

a. air

b. copper

c. iron

d. salt water


10/100

Of the following substances, the best

conductor is

a. air

b. copper

c. iron

d. salt water


11/100

Movement of holes in a semiconductor

a. is like a flow of electrons in the same

direction.

b. is possibly only if the current is high

enough.

c. results in a certain amount of electric

current.

d. causes the material to stopconducting.


12/100

If a material has low resistance, then

a. it is a good conductor.

b. it is a poor conductor.

c. the current flows mainly in the form of

holes.

d. current can flow only in one direction.


13/100

A coulomb

a. represents a current of 1 ampere.

b. flows through a 100-watt light bulb.

c. is equivalent to 1 ampere per second.

d. is an extremely large number of charge

carriers.


14/100

A stroke of lightning

a. is caused by a movement of holes in

an insulator.

b. has a very low current.

c. is a discharge of electrostatic

electricity.

d. builds up between clouds.


15/100

The volt is the unit of

a. current

b. charge

c. electromotive force

d. resistance


16/100

If an EMF of 1 volt is placed across a

resistance of 2 ohms, then the current is

a. half an ampere

b. 1 ampere

c. 2 amperes

d. impossible to determine


17/100

A backward-working electric motor, in

which mechanical rotation is convertedto electricity, is best described as

a. an inefficient, energy wasting device.

b. a motor with voltage connected the

wrong way.

c. an electric generator.

d. a magnetic field.


18/100

In battery, chemical energy can

sometimes be replenished by

a. connecting it to a light bulb.

b. charging it.

c. discharging it.

d. no means known; when a battery is

dead, you must throw it away.


19/100

A fluctuating magnetic field

a. produces an electric current in an

insulator.

b. magnetizes the earth.

c. produces a fluctuating electric field.

d. results from a steady electric current.


20/100

Visible light is converted into electricity

a. in a dry cell.

b. in a wet cell.

c. in an incandescent bulb.

d. in a photovoltaic cell.


21/100

A positive electric pole

a. has a deficiency of electrons.

b. has fewer electrons than the negative

pole.

c. has an excess of electrons.

d. has more electrons than the negative

pole.


22/100

An EMF of 1V

a. cannot drive much current through a

circuit.

b. represents a low resistance.

c. can sometimes produce a large

current.

d. drops to zero in a short time.


23/100

A potentially lethal electric current is on

the order of

a. 0.01 mA.

b. 0.1 mA.

c. 1 mA.

d. 0.1 A.


24/100

A current of 25 A is most likely drawn by

a. a flashlight bulb.

b. a typical household.

c. a utility power plant.

d. a small radio set.


25/100

A piece of wire has a conductance of

20S. Its resistance is

a. 20

b. 0.5

c. 0.05

d. 0.02


26/100

A resistor has a value of 300 ohms. Its

conductance is

a. 3.33 mS

b. 33.3 mS

c. 333 S

d. 0.333 S


27/100

A span of wire 1km long has a

conductance of 0.6 S. What is theconductance of a span of this same wire

that is 3 km long?

a. 1.8 S.

b. 0.6 S.

c. 0.2 S.

d. More information is necessary todetermine this.


28/100

Approximately how much current can a

2-kW generator reliably deliver at 117 V?

a. 17 mA.

b. 234 mA.

c. 17 A.

d. 234 A.


29/100

A circuit breaker is rated for 15 A at 117

V. Approximately how much power doesthis present?

a. 1.76 kW.

b. 1760 kW.

c. 7.8 kW.

d. 0.0078 kW.


30/100

You are told that an air conditioner has

cooled a room by 500 Btu over a certainperiod of time. What is the amount of

energy in kWh?

a. 147 kWh.

b. 14.7 kWh.

c. 1.47 kWh.

d. 0.147 kWh.


31/100

Of the following energy units, the most

often used to define electrical energy is

a. the Btu.

b. the erg.

c. the foot-pound.

d. the kilowatt-hour.


32/100

The frequency of common household ac

in the United States is

a. 60 Hz.

b. 120 Hz.

c. 50 Hz.

d. 100 Hz.


33/100

Half-rectification means that

a. half of the ac wave is inverted.

b. half of the ac wave is cut off.

c. the whole ac wave is inverted.

d. the effective voltage is half the peak

voltage.


34/100

In the output of a half-wave rectifier,

a. half of the ac input wave is inverted.

b. the effective voltage is less than that of

the ac input wave.

c. the effective voltage is the same as

that of the ac input wave.

d. the effective voltage is more than that

of the ac input wave.


35/100

In the output of a full-wave rectifier,

a. half of the ac input wave is inverted.

b. the effective voltage is less than that of

the ac input wave.

c. the effective voltage is the same as

that of the ac input wave.

d. the effective voltage is more than that

of the ac input wave.


36/100

A low voltage, such as 12 V,

a. is never dangerous.

b. is always dangerous.

c. is dangerous if it is ac, but not if it is

dc.d. can be dangerous under certain

conditions.


37/100

Which of the following units can be

represent magnetomotive force?

a. The volt-turn

b. The ampere-turn

c. The gaussd. The gauss-turn


38/100

Which of the following units can

represent magnetic flux density?

a. The volt-turn

b. The ampere-turn

c. The gaussd. The gauss-turn


39/100

A ferromagnetic material

a. concentrates magnetic flux lines within

itself.

b. increases the total magnetomotive

force around a current-carrying wire.c. causes an increase in the current in a

wire.

d. increases the number of ampere-turnsin a wire.


40/100

A coil has 500 turns and carries 75 mA of

current. The magnetomotive force is

a. 37,500 At

b. 375 At

c. 37.5 Atd. 3.75 At


41/100

The attraction or repulsion between two

electrically charged objects is called

a. electromagnetic deflection.

b. electrostatic force.

c. magnetic force.d. electroscopic force.


42/100

The change in the direction of a compass

needle, when a current-carrying wire isbrought near, is called

a. electromagnetic deflection.

b. electrostatic force.c. magnetic force.

d. electroscopic force.


43/100

Suppose a certain current in a

galvanometer causes the compassneedle to deflect by 20 degrees, and then

this current is doubled while the polarity

stays the same. The angle of the needle

deflection will

a. decrease.

b. stay the same.c. increase.

d. reverse direction.


44/100

One important advantage of an

electrostatic meter is the fact that

a. it measures very small currents.

b. it can handle large currents.

c. it can detect and indicate ac voltagesas well as dc voltages.

d. it draws a large current from a power

supply.


45/100

A thermocouple

a. gets warm when dc flows through it.

b. is a thin, straight, special wire.

c. generates dc when exposed to visible

light.d. generates ac when heated.


46/100

An important advantage of an

electromagnet-type meter over apermanent-magnet meter is the fact that

a. the electromagnet meter costs much

less.b. the electromagnet meter need not be

aligned with the earths magnetic field.

c. the permanent-magnet meter has amore sluggish coil.

d. the electromagnet meter is more

rugged.


47/100

Ammeter shunts are useful because

a. they increase meter sensitivity.

b. they make a meter more physically

rugged.

c. they allow for measurement of largecurrents.

d. they prevent overheating of the meter

movement.


48/100

Voltmeters should generally have

a. high internal resistance.

b. low internal resistance.

c. the greatest possible sensitivity.

d. the ability to withstand large currents.


49/100

In order to measure the power supply

voltage that is applied to an electrical

circuit, a voltmeter should be placed

a. in series with the dc circuit that works

from the supply.b. between the negative pole of the supply

and the circuit working from the supply.

c. between the positive pole of the supply

and the circuit working from the supply.

d. in parallel with the circuit that works from

the supply.


50/100

Which of the following will not normally

cause a large error in an ohmmeter

reading?

a. A small voltage between points under

testsb. A slight change in switchable internal

resistance

c. A small changed in the resistance to bemeasured

d. A slight error in the rang switch

position


51/100

The main advantage of a FETVM over a

conventional voltmeter is the fact that the

FETVM

a. can measure lower voltages.

b. draws less current from the circuitunder tests.

c. can withstand higher voltages safely.

d. is sensitive to ac voltage as well as todc voltage.


52/100

Which of the following is not a function of a

fuse?

a. To ensure there is enough current

available for an appliance to work right

b. To make it impossible to use appliancesthat are too large for a given circuit

c. To limit the amount of power that a device

can draw from the electrical circuit

d. To make sure the current drawn by an

appliance cannot exceed a certain limit


53/100

A utility meters motor speed depends

directly on

a. the number of ampere-hours being

used at the time.

b. the number of watt-hours being usedat the time.

c. the number of watts being used at the

time.d. the number of kilowatt-hours being

used at the time.


54/100

A utility meters readout indicates

a. voltages.

b. power.

c. current.

d. energy.


55/100

A typical frequency counter

a. has an analog readout.

b. is accurate to six digits or more.

c. works by indirectly measuring current.

d. works by indirectly measuring voltage.


56/100

A VU meter is never used to get a general

indication of

a. sound intensity.

b. decibels.

c. power in an audio amplifier.d. visible light intensity.


57/100

The meter movement in an illumination

meter directly measures

a. current.

b. voltage.

c. power.d. energy.


58/100

An oscilloscope cannot be used to

indicate

a. frequency.

b. wave shape.

c. energy.d. peak signal voltage.


59/100

Suppose you double the voltage in a

simple dc circuit, and cut the resistance

in half. The current will

a. become four times as great.

b. become twice as great.c. stay the same as it was before.

d. become half as great.


60/100

You can expect to find a wiring diagram

a. on a sticker on the back of a television

receiver.

b. in an advertisement for a n electric

oven.c. in the service/repair manual for a two-

way radio.

d. in the photograph of the front panel ofa stereo hi-fi tuner.


61/100

Given a dc voltage source delivering 24V

and resistance of 3.3 k, what is the

current?

a. 0.73 A

b. 138 Ac. 138 mA

d. 7.3 mA


62/100

Suppose the resistance is 472 , and the

current is 875 mA. The source voltage

must therefore be

a. 413 V.

b. 0.539 V.c. 1.85 V.

d. none of the above.


63/100

Suppose the dc voltage is 550 mV and

the current is 7.2 mA. Then the

resistance is

a. 0.76

b. 76 c. 0.0040

d. none of the above.


64/100

Given a dc voltage of 3.5 kV and a

resistance of 220 , what is the current?

a. 16 mA

b. 6.3 mA

c. 6.3 Ad. None of the above


65/100

Suppose the resistance is 473,332 , and

the current flowing through it is 4.4 mA.

The best expression for the voltage of the

source is

a. 2082 V.b. 110 kV.

c. 2.1 kV.

d. 2.08266 kV.


66/100

A source delivers 12 V and the current is

777 mA. The best expression for the

resistance is

a. 15 .

b. 15.4 .c. 9.3 .

d. 9.32 .


67/100

Suppose the voltage is 250 V and the

current is 8.0 mA. The power dissipated

by the potentiometer is

a. 31 mW.

b. 31 W.c. 2.0 W.

d. 2.0 mW.


68/100

Suppose the voltage from the source is

12 V and the potentiometer is set for 470

. The power dissipated in the resistance

is approximately

a. 310 mW.b. 25.5 mW.

c. 39.2 W.

d. 3.26 W.


69/100

If the current through the potentiometer

is 17 mA and its resistance is set to 1.22

k, what is the power dissipated by it?

a. 0.24 W

b. 20.7 Wc. 20.7 mW

d. 350 mW


70/100

Suppose six resistors are hooked up in

series, and each of them has a value of

540 . What is the resistance across the

entire combination?

a. 90 b. 3.24 k

c. 540

d. None of the above


71/100

If four resistors are connected in series,

each with a value of 4.0 k, the total

resistance is

a. 1 k.

b. 4 k.c. 8 k.

d. 16k.


72/100

Suppose you have three resistors in

parallel, each with a value of 0.069 M.

Then the total resistance is

a. 23 .

b. 23 k.c. 204 .

d. 0.2 M.


73/100

Imagine three resistors in parallel, with

values of 22 , 27 , and 33 . If a 12-V

battery is connected across this

combination, what is the current drawn

from the battery?

a. 1.4 A

b. 15 mAc. 150 mA

d. 1.5 A


74/100

Imagine three resistor, with values of 47

, 68 , and 82 , connected in series

with a 50-V dc generator. The total power

consumed by this network of resistors is

a. 250 mW.b. 13 mW.

c. 13 W.

d. impossible to determine from the datagiven.


75/100

Suppose you have an unlimited supply of

1-W, 100- resistors. You need to get a

100-, 10-W resistor. This can be done

most cheaply by means of a series-

parallel matrix of

a. 3 x 3 resistors.

b. 4 x 3 resistors.c. 4 x 4 resistors.

d. 2 x 5 resistors.


76/100

Suppose you have an unlimited supply of 1-

W, 1000- resistors, and you need a 500-

resistance rated at 7 W or more. This can bedone by assembling

a. four sets of two resistors in series, andconnecting these four sets in parallel.

b. four sets of two resistors in parallel, and

connecting these four sets in series.

c. a 3 x 3 series-parallel matrix of resistors.

d. a series-parallel matrix, but something

different than those described above.


77/100

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 to

a. make a 2 x 2 series-parallel matrix.b. connect three of the resistors in

parallel.

c. make a 3 x 3 series-parallel matrix.d. do something other than any of the

above.


78/100

Good engineering practice usually

requires that a series-parallel resistive

network be assembled

a. from resistors that are all different.

b. from resistors that are all identical.c. from a series combination of resistors

in parallel but not from a parallel

combination of resistors in series.d. from a parallel combination of

resistors in series, but not from a series

combination of resistors in parallel.


79/100

In a series-connected string of ornament

bulbs, if one bulb gets shorted out, which

of the following will occur?

a. All the other bulbs will go out.

b. The current in the string will go up.c. The current in the string will go down.

d. The current in the string will stay the

same.


80/100

Imagine that four resistors are connected

in series across a 6.0-V battery, and the

ohmic values are R1=10 , R2=20 ,

R3=50, and R4=100. What is the

voltage across the resistance R2?

a. 0.18 V

b. 33 mV

c. 5.6 mVd. 0.67 V


81/100

Fill in the blank in the following sentence

to make it true: In a series or parallel dc

circuit, the sum of the ______s in each

component is equal to the total ______

provided by the power supply.

a. current

b. voltage

c. wattaged. resistance


82/100

In a voltage divider network, the total

resistance

a. should be large to minimize current

drain.

b. should be as small as the powersupply will allow.

c. is not important.

d. should be such that the current is keptto 100 mA.


83/100

The maximum voltage output from a

voltage divider

a. is a fraction of the power supply

voltage.

b. depends on the total resistance.c. is equal to the supply voltage.

d. depends on the ratio of resistances.


84/100

Proper biasing in an amplifier circuit

a. causes it to oscillate.

b. prevents an impedance match.

c. can be obtained using a voltage divider

network.d. maximizes current flow.


85/100

A transistor can be protected from

needless overheating by

a. current-limiting resistor.

b. bleeder resistors.

c. maximizing the drive.d. shorting out the power supply when

the circuit is off.


86/100

A bleeder resistor

a. is connected across the capacitor in a

power supply.

b. keeps a transistor from drawing too

much current.c. prevents an amplifier from being

overdriven.

d. optimizes the efficiency of an amplifier.


87/100

Carbon-composition resistors

a. can handle gigantic levels of power.

b. have capacitance or inductance along

with resistance.

c. have essentially no capacitance orinductance.

d. work better for ac than for dc.


88/100

A logical place for a wirewound resistor

is

a. in a radio-frequency amplifier.

b. in a circuit where a non-inductive

resistor is called for.c. in a low-power radio-frequency circuit.

d. in a high power dc circuit.


89/100

A metal-film resistor

a. is made using a carbon-based paste.

b. does not have much inductance.

c. can dissipate large amounts of power.

d. has considerable inductance.


90/100

What type of resistor, or combination of

resistors, would use as the meter-

sensitivity control in a test instrument,

when continuous adjustment is desired?

a. A set of switchable , fixed resistorsb. A linear-taper potentiometer

c. An audio-taper potentiometer

d. A wirewound resistor


91/100

What type of resistor, or combination of

resistors, would you use as the volume

control in a stereo compactdisc (CD)

player?

a. A set of switchable , fixed resistorsb. A linear-taper potentiometer

c. An audio-taper potentiometer

d. A wirewound resistor


92/100

If a sound triples in actual power level,

approximately what is this, expressed in

decibels?

a. +3 dB

b. +5 dBc. +6 dB

d. +9 dB


93/100

Suppose a sound changes in volume by -

13 dB. If the original sound power is 1.0

W, what is the final sound power?

a. 13 W

b. 77 mWc. 50 mW

d. There is not enough information given

here to answer the question.


94/100

The sound from a portable radio is at a

level of 50 dB. How many times the

threshold of hearing is this, in terms of

actual sound power?

a. 50b. 169

c. 5,000

d. 100,000


95/100

An advantage of a rheostat over a

potentiometer is the fact that

a. a rheostat can handle higher

frequencies.

b. a rheostat is more precise.c. a rheostat can handle more current.

d. a rheostat works better with dc.


96/100

A resistor is specified as having a value

of 68 , but is measured with an

ohmmeter as 63 . The value is off by

which of the following percentages?

a. 7.4 %b. 7.9 %

c. 5 %

d. 10 %


97/100

Suppose a resistor is rated at 3.3 k

5%. This means it can be expected to

have a value between

a. 2970 and 3630 .

b. 3295 and 3305 .c. 3135 and 3465 .

d. 2.8 k and 3.8 k.


98/100

A package of resistor is rated at 56

10%. You test them with an ohmmeter.

Which of the following values indicates a

reject?

a. 50.0 b. 53.0

c. 59.7

d. 61.1

f 680


99/100

A resistor has a value of 680 , and you

expect that it will have to draw 1 mA

maximum continuous current in a circuit

youre building. What power rating is

good for this application, but not

needlessly high?

a. W

b. Wc. 1 W

d. 2 W

S 1 k i t ill di i t 1 05


100/100

Suppose a 1-k resistor will dissipate 1.05

W, and you have a good supply of 1-W

resistors of various ohmic values. If theresroom for 20% resistance error, the cheapest

solution is to use

a. four 1-k, 1-W resistors in series-parallel.

b. a pair of 2.2-k, 1-W resistors in parallel.

c. a set of three 3.3-k, 1-W resistors in

parallel.d. a single 1-k, 1-W resistors, because all

manufacturers allow for a 10% margin of safety

Gibilisco chapter 1

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Transcript of Gibilisco chapter 1