# Quiz 11: Inductors

Physics & Astronomy

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Q 2Q 2

The energy stored in an inductor's electromagnetic field is produced by the inductor's current.

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Q 6Q 6

The energy stored in an inductor's electromagnetic field is produced by the resistance of the inductor's winding.

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Q 10Q 10

If an inductor is placed in an ac circuit, the ac voltage across the inductor leads the ac current through it.

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Q 16Q 16

What is the total inductance if a 50 mH inductor is connected in series with a 15 mH inductor?
A)50 mH
B)65 mH
C)11.5 mH
D)15 mH

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Multiple Choice

Q 17Q 17

What is the maximum current in a 12 mH inductor if it is connected in series with a 10 k▲ resistor and a 15 VDC source?
A)2.2 mA
B)1.2 mA
C)6.32 mA
D)1.5 mA

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Multiple Choice

Q 18Q 18

If an inductor has an ac current flowing through it, the magnetic field is .
A)collapsed
B)steady
C)moving from south to north
D)constantly changing

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Multiple Choice

Q 19Q 19

Do iron -core inductors or air -core inductors generally have the larger inductance?
A)neither; iron -core inductors and air -core inductors have the same inductance
B)iron core
C)air core
D)There is no way to tell.

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Multiple Choice

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Q 21Q 21

In an inductive circuit, the lags the .
A)voltage, reactance
B)current, resistance
C)voltage, resistance
D)current, voltage

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Q 22Q 22

If a 27 m H inductor has a reactance of 5.5 k▲, the frequency equals .
A)3.24 kHz
B)324 Hz
C)932 Hz
D)32.4 kHz

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Multiple Choice

Q 23Q 23

What is one time constant for a 10 mH inductor connected in series with a 47 k▲ resistor?
A)213 µS
B)470 S
C)0.213 µS
D)470 mS

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Multiple Choice

Q 24Q 24

How many time constants will it take to completely collapse an inductor's magnetic field?
A)1
B)4
C)3
D)5

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Q 25Q 25

What is the inductive reactance of a 0.2 mH inductor operating at 1 kHz?
A)1.26 ▲
B)1.26 k▲
C)126 k▲
D)126 ▲

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Multiple Choice

Q 26Q 26

What is the inductive reactance of an inductor that drops 12 VRMS and carries 50 mARMS?
A)240 ▲
B)60 ▲
C)600 ▲
D)6 ▲

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Multiple Choice

Q 27Q 27

What is the inductance of a 20 mH inductor connected in parallel with a 50 mH inductor?
A)50 mH
B)70 mH
C)20 mH
D)14.3 mH

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Multiple Choice

Q 28Q 28

Connecting a inductance. inductor in
With a 100 m H inductor produces a 65 m H
A)35 mH, series
B)186 mH, series
C)35 mH, parallel
D)186 mH, parallel

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Multiple Choice

Q 29Q 29

If an inductor carries 100 mADC of current when connected across a 30 VDC source, then what is its resistance?
A)0 ▲
B)300 ▲
C)30 ▲
D)60 ▲

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Multiple Choice

Q 30Q 30

If two 2.5 mH inductors are connected in series with a 4.7 k▲ resistor and the source voltage is 100 VDC, what is the circuit's maximum current?
A)1.1 mA
B)21.3 mA
C)63.2 mA
D)7.9 mA

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Q 31Q 31

What is the inductive reactance of a 150 mH inductor operating at 10 kHz?
A)6280 ▲
B)9420 ▲
C)8450 ▲
D)1500 ▲

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Multiple Choice

Q 32Q 32

What is the time constant for a 50 mH inductor and 5 k▲ resistor connected in series?
A)10 µs
B)250 s
C)100 s
D)10 ms

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Q 33Q 33

What is the total inductance of a 40 mH inductor and a 24 mH inductor connected in parallel?
A)32 mH
B)150 mH
C)64 mH
D)15 mH

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Multiple Choice

Q 34Q 34

An 0.05 µH inductance is larger than a _.
A)0.000005 H inductance
B)0.00005 H inductance
C)0.0000005 H inductance
D)0.000000008 H inductance

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Q 35Q 35

A 0.33 mH inductance is smaller than a _.
A)33 pH inductance
B)0.05 mH inductance
C)330 pH inductance
D)0.0005 H inductance

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Q 36Q 36

What is the total inductance of four 10 mH inductors connected in series?
A)2.5 mH
B)40 mH
C)40,000 µH
D)250 mH

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Multiple Choice

Q 37Q 37

If a 1 mH, 3.3 mH, and 0.1 mH inductor are connected in parallel, LT equals .
A)less than 0.1 mH
B)5.3 mH
C)4.4 mH
D)greater than 3.3 mH

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Multiple Choice

Q 38Q 38

If an inductor, resistor and switch are connected in series to a 12 V battery, what is the magnitude of the inductor's voltage at the instant that the switch is closed?
A)4 V
B)0 V
C)6 V
D)12 V

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Multiple Choice

Q 39Q 39

If two inductors are connected in a series AC circuit, which inductor drops more voltage?
A)It depends upon the frequency.
B)It depends upon the source voltage.
C)the larger inductance
D)the smaller inductance

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Multiple Choice

Q 40Q 40

What is the total inductance of a 14 mH, 22 mH and 45 mH inductor connected in series?
A)81 µH
B)81 mH
C)7.2 mH
D)20 mH

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Multiple Choice

Q 41Q 41

If a 50 mH inductor is in series with a 50 k▲ resistor across a 50 VDC source, what is the maximum current that will flow in the circuit?
A)10 mA
B)1 µA
C)1 mA
D)100 µA

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Multiple Choice

Q 42Q 42

If a 25 mH inductor drops 50 V while operating at 400 Hz, what is XL?
A)6.28 k▲
B)62.8 k▲
C)628 ▲
D)62.8 ▲

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Multiple Choice

Q 43Q 43

If a 15 µH inductor has a 2.2 K▲ reactance, the frequency equals .
A)23.3 kHz
B)4.28 MHz
C)4.28 kHz
D)23.3 MHz

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Multiple Choice

Q 44Q 44

How many time constants will it take to completely build a magnetic field around an inductor?
A)1
B)2
C)3
D)4
E)5

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Multiple Choice

Q 45Q 45

What is the reactance of a 100 µH inductor operating at 100 kHz?
A)62.8 k▲
B)6.28 ▲
C)62.8 ▲
D)infinite ▲

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Multiple Choice

Q 46Q 46

What is the reactance of an inductor that carries 1.25 mAP and drops 25 VP at 100 Hz?
A)20 k▲
B)3.13 k▲
C)15.7 k▲
D)31.3 ▲

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Multiple Choice

Q 47Q 47

What is the total inductance of a 25 mH inductor connected in parallel with a 100 mH inductor?
A)less than 20 mH
B)more than 125 mH
C)20 mH
D)125 mH

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Multiple Choice

Q 48Q 48

Connecting a inductor in
With a 70 mH inductor produces a 100 mH inductance.
A)233 mH, series
B)233 mH, parallel
C)30 mH, series
D)30 mH, parallel

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Multiple Choice

Q 49Q 49

If an inductor carries 150 mADC of current when connected across a 65 VDC source, what is its resistance?
A)30 ▲
B)26.7 ▲
C)433 ▲
D)65 ▲

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Multiple Choice

Q 50Q 50

Figure 11 -1V
-How much current flows in the circuit in Figure 11 -1 if connected to a 12 VPP, 2 kHz source?
A)60.5 mAp -p
B)4.77 mAp -p
C)126 mAp -p
D)10.1 mAp -p

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Multiple Choice

Q 51Q 51

Figure 11 -1V
-What is the total inductance in Figure 11 -1?
A)95 mH
B)15.8 mH
C)225 mH
D)12.7 mH

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Multiple Choice

Q 52Q 52

Inductors .
A)pass direct current
B)have high reactance to direct current
C)block direct current
D)have a high resistance to direct current

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Multiple Choice

Q 53Q 53

Which type of inductor core material is likely to produce the least inductance?
A)air
B)iron
C)ferrite

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Q 54Q 54

In a switch -mode power supply the role of the inductor is
A)surge protection
B)to produce a constant load current
C)to function as a low -pass filter
D)to function as a high -pass filter

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Multiple Choice

Q 55Q 55

When inductors are connected in series, their total inductance acts like:
A)resistance connected in series -parallel.
B)resistance connected in parallel.
C)resistance connected in series.
D)all of these.

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Multiple Choice

Q 56Q 56

When inductors are connected in parallel, their total inductance acts like:
A)resistance connected in parallel.
B)resistance connected in series -parallel.
C)resistance connected in series.
D)all of these.

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Multiple Choice

Q 57Q 57

The time constant of an inductor is:
A)the time required for voltage or current to increase to 63% or to decrease to 37%.
B)inversely proportional to the resistance in the circuit.
C)directly proportional to the inductance in the circuit.
D)all of these.

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Multiple Choice

Q 58Q 58

The time constant for an inductor for each time period:
A)is a constant value.
B)corresponds to a 37% of the decrease in value.
C)corresponds to a 63% of the increase in value.
D)all of these.

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Multiple Choice

Q 59Q 59

Reactive power (Pr)in an inductor is defined as the rate at which an inductor stores or returns energy and is measured in:
A)current per time constant.
B)volt -ampere reactive.
C)watts reactive.
D)volts per time constant.

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Multiple Choice

Q 60Q 60

In an inductive AC circuit, the phase relationship between the voltage and the current is such that the:
A)voltage is lagging the current.
B)voltage is 360 degrees out of phase with voltage.
C)current is 180 degrees out of phase with voltage.
D)current is lagging the voltage.

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Multiple Choice

Q 61Q 61

The most commonplace use for inductors in electronics:
A)blocks DC voltages.
B)blocks AC voltages.
C)passes DC voltages.
D)passes AC voltages.

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Q 62Q 62

Stray capacitance for a coil becomes a problem:
A)with high frequencies.
B)with low frequencies.
C)with ac circuits.
D)at resonant frequencies.

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Multiple Choice

Q 63Q 63

The ripple voltage as measured at the output of a power supply has increased. Which of the following could be the problem?
A)load resistance has dropped
B)partial shorting of the windings of the filtering coil
C)resistance of the coil has decreased
D)either A or B

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Multiple Choice

Q 64Q 64

It has been determined that the source of audible noise for a radio is due to the power supply voltage. How can an inductor be configured to eliminate this noise?
A)An inductor will not affect the noise.
B)Connect the inductor in series with the radio power wire.
C)Connect the inductor in parallel with the radio.
D)both B and C

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Multiple Choice

Q 65Q 65

Determination of an inductor's value can be had by what method(s)?
A)Use an inductance meter.
B)Connect the inductor in series with a known value of resistance, apply a square wave of a known voltage value, then use the time constant formula.
C)Apply a signal of a known frequency and voltage, then use Ohm's law and the inductive reactance formula.
D)any of the above

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Multiple Choice

Q 66Q 66

An inductor can be simulated using resistors, capacitors, and operational amplifiers. Ths circuit is called a _ _.
A)oscillator
B)gyrator
C)modulator
D)inducer

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Multiple Choice