# Quiz 21: Alternating Current Circuits and Electromagnetic Waves

Physics & Astronomy

Q 1Q 1

What is the effective (rms) current value for an AC current with an amplitude of 10 A?
A)28 A
B)3.1 A
C)7.1 A
D)14 A

Free

Multiple Choice

C

Q 2Q 2

In an AC series circuit, the current in a pure resistor differs in phase with the applied voltage by what angle?
A)zero
B)45
C)90
D)180

Free

Multiple Choice

A

Q 3Q 3

The rate of heat dissipation in an AC circuit with resistance, R, and effective current, I

_{rms}, is given by which of the following? A)0.5 * (I_{rms})^{2}R B)(I_{rms})^{2}R C)2.0 * (I_{rms})^{2}R D)4.0 * (I_{rms})^{2}RFree

Multiple Choice

B

Q 4Q 4

An AC voltage source, with a peak output of 200 V, is connected to a 50-W resistor.What is the effective (or rms) current in the circuit?
A)2.8 A
B)4.0 A
C)5.6 A
D)2.0 A

Free

Multiple Choice

Q 5Q 5

An AC voltage source, with a peak output of 200 V, is connected to a 50-W resistor.What is the rate of energy dissipated due to heat in the resistor?
A)200 W
B)400 W
C)566 W
D)800 W

Free

Multiple Choice

Q 6Q 6

The rms current is equal to the direct current that:
A)produces the same average voltage across a resistor as in an AC circuit.
B)dissipates an equal amount of energy in a resistor at the same rate as in an AC circuit.
C)provides the same average current in a resistor as in an AC circuit.
D)results in the same peak power in a resistor as in an AC circuit.

Free

Multiple Choice

Q 7Q 7

An AC voltage source, with a peak output of 120 V, results in dissipation of energy in a resistor at rate of 100 W.What is the value of the resistance?
A)144 W
B)120 W
C)100 W
D)72 W

Free

Multiple Choice

Q 8Q 8

The peak voltage of an AC source is 200 V.What is the rms voltage?
A)282 V
B)200 V
C)141 V
D)100 V

Free

Multiple Choice

Q 9Q 9

In the typical household AC voltage of 120 V, what is the peak voltage?
A)240 V
B)170 V
C)120 V
D)85 V

Free

Multiple Choice

Q 10Q 10

The frequency in an AC series circuit is doubled.By what factor does this change the capacitive reactance?
A)1/2
B)1/4
C)2
D)4

Free

Multiple Choice

Q 11Q 11

In an AC series circuit the capacitive reactance is 200 W and frequency is 100 Hz.What is the capacitance?
A)3.2 mF
B)6.28 mF
C)8.0 mF
D)50.0 mF

Free

Multiple Choice

Q 12Q 12

A 12.0-mF capacitor is connected to an AC source with an rms voltage of 120 V and a frequency of 60.0 Hz.What is the rms current in the capacitor?
A)1.41 A
B)0.768 A
C)0.543 A
D)0 A

Free

Multiple Choice

Q 13Q 13

When a 50-mF capacitor is attached to an AC source, its capacitive reactance is 40 W.If instead a 100-mF capacitor is attached to the same source, what will be its capacitive reactance?
A)80 O
B)57 O
C)28 O
D)20 O

Free

Multiple Choice

Q 14Q 14

In a capacitor in an AC circuit, the voltage:
A)leads the current by 90.
B)lags the current by 90.
C)may lead or lag the current depending on the frequency.
D)is in phase with 70.7% of the current.

Free

Multiple Choice

Q 15Q 15

In the inductor of a 60-Hz AC series circuit, the peak voltage precedes the peak current in each cycle by what time interval?
A)2.1 * 10

^{-3}s B)4.2 * 10^{-3}s C)8.3 * 10^{-3 }s D)1.7 * 10^{-3}sFree

Multiple Choice

Q 16Q 16

In an AC series circuit, the voltage in the inductor differs in phase with the voltage in the capacitor by what angle?
A)zero
B)45
C)90
D)180

Free

Multiple Choice

Q 17Q 17

In an AC series circuit the inductive reactance is 50 W and the frequency is 100 Hz.What is the inductance in the circuit?
A)80 mH
B)240 mH
C)500 mH
D)740 mH

Free

Multiple Choice

Q 18Q 18

The current in an inductor connected to an AC voltage source lags the voltage.This lag is caused by the:
A)back emf in the coil.
B)voltage across the coil.
C)time required for electrical signals to travel through all the coils of an inductance.
D)resistance of the coil.

Free

Multiple Choice

Q 19Q 19

What is the impedance of an AC series circuit that is constructed of a 10.0-W resistor along with 12.0 W inductive reactance and 7.0 W capacitive reactance?
A)37.0 W
B)27.7 W
C)27.1 W
D)11.2 W

Free

Multiple Choice

Q 20Q 20

What is the phase angle of an AC series circuit that is constructed of a 10.0-W resistor along with 12.00 W inductive reactance and 7.00 W capacitive reactance?
A)26.6
B)18.4
C)87.0
D)63.4

Free

Multiple Choice

Q 21Q 21

An AC series circuit has 12.0 W resistance, 15.00 W inductive reactance and 10.00 W capacitive reactance.If an effective (rms) emf of 120 V is applied, what is the effective (rms) current value?
A)5.31 A
B)9.23 A
C)10.8 A
D)26.0 A

Free

Multiple Choice

Q 22Q 22

Consider an AC series circuit containing a coil, capacitor and resistance.Tripling the frequency will change the inductive reactance by what factor?
A)1/3
B)1.0
C)1.73
D)3.0

Free

Multiple Choice

Q 23Q 23

Consider an AC series circuit containing a coil, capacitor and resistance.Tripling the frequency will change the capacitive reactance by what factor?
A)1/3
B)1.0
C)1.73
D)3.0

Free

Multiple Choice

Q 24Q 24

Consider an AC series circuit containing a coil, capacitor and resistance.Tripling the frequency will change the circuit's impedance by what factor?
A)1/3
B)1.0
C)3.0
D)Information is insufficient to determine answer.

Free

Multiple Choice

Q 25Q 25

A resistor and capacitor are connected in series with an applied AC voltage source.Separate voltmeter readings across the resistor and capacitor give values of 50 V and 75 V (rms), respectively.What is the effective (rms) voltage of the source?
A)25 V
B)63 V
C)90 V
D)125 V

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Multiple Choice

Q 26Q 26

A resistor, inductor, and capacitor are connected in series, each with effective (rms) voltage of 65 V, 140 V, and 80 V, respectively.What is the value of the effective (rms) voltage of the applied source in the circuit?
A)48 V
B)88 V
C)95 V
D)285 V

Free

Multiple Choice

Q 27Q 27

A resistor, inductor, and capacitor are connected in series, each with an effective (rms) voltage of 65 V, 140 V, and 80 V, respectively.What is the magnitude of the phase angle in this circuit?
A)22
B)28
C)37
D)43

Free

Multiple Choice

Q 28Q 28

In an AC circuit, the ratio of average current to maximum current is:
A)zero.
B)0.5.
C)0.707.
D)1.0.

Free

Multiple Choice

Q 29Q 29

A series circuit has equal values for resistance, capacitive reactance, and inductive reactance.The phase angle for this circuit is:
A)60.
B)-60.
C)180.
D)not given.

Free

Multiple Choice

Q 30Q 30

In an RLC series circuit the capacitive reactance is 24 W.If the AC frequency doubles, what will be the resulting capacitive reactance?
A)24 W
B)12 W
C)48 W
D)Additional information is need to find the value.

Free

Multiple Choice

Q 31Q 31

In an RLC series circuit the phase angle between the current and voltages is 30.If the AC frequency doubles, what is the resulting phase angle?
A)30
B)more than 30
C)less than 30
D)Additional information is needed to reach a determination.

Free

Multiple Choice

Q 32Q 32

In an RLC series circuit, if the AC frequency is increased to a very large value, what value does the phase angle between the current and voltage approach?
A)90
B)0
C)-90
D)45

Free

Multiple Choice

Q 33Q 33

In an RLC series circuit, if the AC frequency is decreased to a very small value, what value does the phase angle between the current and voltage approach?
A)90
B)0
C)-90
D)45

Free

Multiple Choice

Q 34Q 34

An AC series circuit has 12.0 W resistance, 15.00 W inductive reactance and 10.00 W capacitive reactance.If an effective (rms) emf of 120 V is applied, what is the power output?
A)1 540 W
B)1 300 W
C)1 160 W
D)1 020 W

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Multiple Choice

Q 35Q 35

The power dissipated in an AC series circuit increases as the phase angle approaches what value?
A)zero
B)45
C)90
D)180

Free

Multiple Choice

Q 36Q 36

The power factor in an AC series circuit is equal to which of the following ratios?
A)resistance to inductive reactance
B)capacitive reactance to inductive reactance
C)inductive reactance to capacitive reactance
D)resistance to impedance

Free

Multiple Choice

Q 37Q 37

A resistor, inductor and capacitor are connected in series, each with effective (rms) voltage of 65 V, 140 V and 80 V, respectively.If the resistor is rated at 24 W, what is the average power dissipated in the circuit?
A)88 W
B)176 W
C)238 W
D)323 W

Free

Multiple Choice

Q 38Q 38

What is the average power dissipation in a series RC circuit if R = 5.00 kW, C = 2.00 µF, and V = (170 V) cos 300t?
A)2.60 W
B)2.74 W
C)28.2 W
D)157 W

Free

Multiple Choice

Q 39Q 39

A 200-W resistor is connected in series with a 10-µF capacitor and a 60-Hz, 120-V (rms) line voltage.If electrical energy costs 5.0¢ per kWh, how much does it cost to leave this circuit connected for 24 hours?
A)62¢
B)31¢
C)5.2¢
D)3.1¢

Free

Multiple Choice

Q 40Q 40

Resonance occurs in an AC series circuit when which of the following conditions is met?
A)resistance equals capacitive reactance
B)resistance equals inductive reactance
C)capacitive reactance equals inductive reactance
D)capacitive reactance equals zero

Free

Multiple Choice

Q 41Q 41

An AC series circuit contains a resistor of 20 W, a capacitor of 0.75 mF and an inductor of 120 mH.What frequency should be used to create a resonance condition in the circuit?
A)160 Hz
B)320 Hz
C)640 Hz
D)530 Hz

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Multiple Choice

Q 42Q 42

A series RLC AC circuit is at resonance.It contains a resistor of 30 W, a capacitor of 0.35 mF and an inductor of 90 mH.If an effective (rms) voltage of 150 V is applied, what is the effective (rms) current when the circuit is in resonance?
A)3.3 A
B)5.0 A
C)9.4 A
D)16.1 A

Free

Multiple Choice

Q 43Q 43

An AC series circuit contains a resistor of 20 W, an inductor of 30 mH and a variable capacitor.If the frequency of the applied voltage is 500 Hz, to what setting should the capacitor be set if resonance is achieved?
A)0.8 µF
B)1.6 µF
C)2.4 µF
D)3.4 µF

Free

Multiple Choice

Q 44Q 44

A series RLC circuit in a radio is in resonance with AM 600 kHz.If the radio station is changed to AM 1 200 kHz, by what factor must the capacitance be multiplied to again achieve resonance?
A)4
B)2
C)1/2
D)1/4

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Multiple Choice

Q 45Q 45

Find the resonant frequency for a series RLC circuit where R = 20.0 W, C = 10.0 µF, and L = 4.0 mH.
A)507 Hz
B)796 Hz
C)1.59 kHz
D)5.00 kHz

Free

Multiple Choice

Q 46Q 46

What is the average power dissipation in an RLC series circuit in which R = 100 W, L = 0.1 H, and C = 10 µF driven at resonance by a 100-V (rms) source?
A)100 W
B)500 W
C)1 000 W
D)2 W

Free

Multiple Choice

Q 47Q 47

An AM radio tuning circuit has a coil with an inductance of 6.00 mH and a capacitor set at 7.50 * 10

^{-6}mF.What frequency will it detect? A)550 kHz B)750 kHz C)1 060 kHz D)1 520 kHzFree

Multiple Choice

Q 48Q 48

An FM radio tuning circuit has a coil with an inductance of 0.003 0 mH.What is the value of the capacitance if the set is tuned to 98 MHz?
A)1.8 * 10

^{-6}mF B)12 * 10^{-6}mF C)0.98 * 10^{-6}mF D)0.88 * 10^{-6}mFFree

Multiple Choice

Q 49Q 49

Which of the following combinations of circuit components can be used to make a tuner for a radio, to select the desired frequency?
A)fixed inductor, variable resistor
B)fixed resistor, variable inductor
C)fixed inductor, variable capacitor
D)fixed capacitor, variable resistor

Free

Multiple Choice

Q 50Q 50

When an RLC series circuit is in resonance, its impedance is:
A)zero.
B)equal to its resistance.
C)a maximum.
D)p/2 W.

Free

Multiple Choice

Q 51Q 51

A series RLC circuit has a inductive reactance of 4 W and a capacitive reactance of 1/4 W. By what factor should the AC frequency be changed to put this circuit into resonance?
A)4
B)1/4
C)1/2
D)This circuit cannot be made to achieve resonance.

Free

Multiple Choice

Q 52Q 52

The primary winding of an electric train transformer has 400 turns, and the secondary has 50.If the input voltage is 120 V(rms), what is the output voltage?
A)480 V
B)60 V
C)15 V
D)10 V

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Multiple Choice

Q 53Q 53

A transformer consists of a 500-turn primary coil and a 2 000-turn secondary coil.If the current in the secondary is 3.00 A, what is the primary current?
A)0.750 A
B)1.33 A
C)12.0 A
D)48.0 A

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Multiple Choice

Q 54Q 54

An AC power generator produces 50 A (rms) at 3 600 V. The voltage is stepped up to 100 000 V by an ideal transformer, and the energy transmitted through a long-distance power line with a total resistance of 100 W.What is the rms current in the long-distance line?
A)1.0 A
B)1.8 A
C)24 A
D)1 000 A

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Multiple Choice

Q 55Q 55

An AC power generator produces 25 A (rms) at 3 600 V.The energy is transmitted through a long-distance power line, which has a total resistance of 100 W.What percentage of the power delivered by the generator is dissipated as heat in the long-distance line if a step-up transformer is not used?
A)0.09%
B)1.8%
C)32%
D)69%

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Multiple Choice

Q 56Q 56

A transformer is to be designed to increase the 30-kV (rms) output of a generator to the transmission line voltage of 345 kV (rms).If the primary winding has 80 turns, how many turns must the secondary have?
A)6
B)70
C)920
D)9 200

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Multiple Choice

Q 57Q 57

An ideal transformer is one that:
A)has a turn ratio, N

_{2}/N_{1}, equal to 1. B)works with direct current. C)experiences no power loss. D)has an output frequency of 60 Hz.Free

Multiple Choice

Q 58Q 58

Which one of the following scientists made the theoretical prediction that electromagnetic waves travel through a vacuum at the speed of light?
A)Hertz
B)Faraday
C)Maxwell
D)Lenz

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Multiple Choice

Q 59Q 59

Which one of the following scientists first built and operated devices that could emit and detect man-made electromagnetic radiation?
A)Hertz
B)Ampere
C)Maxwell
D)Lenz

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Multiple Choice

Q 60Q 60

Maxwell developed his theory of electromagnetism by combining previous discoveries.He added his own original hypothesis that:
A)electric charges produce electric fields.
B)moving electric charges produce magnetic fields.
C)changing electric fields produce magnetic fields.
D)changing magnetic fields produce electric fields.

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Multiple Choice

Q 61Q 61

Maxwell guessed that visible light was an electromagnetic wave because of its:
A)frequency.
B)wavelength.
C)speed.
D)energy.

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Multiple Choice

Q 62Q 62

An electromagnetic wave is made up of which of the following oscillating quantities?
A)electrons only
B)electric fields only
C)magnetic fields only
D)electric and magnetic fields

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Multiple Choice

Q 63Q 63

An electromagnetic wave with a peak electric field component of 1.2 * 10

^{2}N/C has what associated peak magnetic field value? (e_{0}= 8.85 * 10^{-12}C^{2}/Nm^{2},^{ }m_{0}= 4p * 10^{-7}Tm/A and c = 3.00 * 10^{8}m/s) A)4.0 * 10^{-7}T B)3.6 * 10^{10 }T C)2.5 * 10^{6}T D)2.8 * 10^{-11 }TFree

Multiple Choice

Q 64Q 64

Which condition of motion must be met with regard to a charged particle if it is in the process of emitting electromagnetic radiation?
A)moves at constant velocity
B)accelerates
C)moves at the speed of light
D)moves parallel to a uniform magnetic field

Free

Multiple Choice

Q 65Q 65

The electric field, , in an electromagnetic wave is oriented in what direction with respect to its associated magnetic field, ?
A) parallel to
B) anti-parallel to
C) perpendicular to
D) at a 45 angle to

Free

Multiple Choice

Q 66Q 66

An electromagnetic wave with a peak magnetic field component of 1.5 * 10

^{-7}T has an associated peak electric field component of what value? (m_{0}= 4p * 10^{-7}Tm/A, e_{0}= 8.85 * 10^{-12}C^{2}/Nm^{2}and c = 3.00 * 10^{8}m/s) A)0.50 * 10^{-15}N/C B)2.00 * 10^{-5 }N/C C)2.20 * 10^{4}N/C D)45 N/CFree

Multiple Choice

Q 67Q 67

An electromagnetic wave with a peak magnetic field component of 1.5 * 10

^{-7}T carries what average power per unit area? (m_{0}= 4p * 10^{-7 }Tm/A, e_{0}= 8.85 * 10^{-12}C^{2}/Nm^{2}and c = 3.00 * 10^{8}m/s) A)12 W/m^{2}B)2.7 W/m^{2}C)3.0 W/m^{2}D)1.3 W/m^{2}Free

Multiple Choice

Q 68Q 68

A radio wave transmits 1.2 W/m

^{2}average power per unit area.What is the peak value of the associated magnetic field? (m_{0}= 4p * 10^{-7}Tm/A and c = 3.00 * 10^{8}m/s) A)1.0 * 10^{-7}T B)8.4 * 10^{-3 }T C)1.2 T D)30 TFree

Multiple Choice

Q 69Q 69

How is the direction of propagation of an electromagnetic wave oriented relative to the associated and fields?
A)parallel to both and
B)perpendicular to both and
C)parallel to , perpendicular to
D)parallel to , perpendicular to

Free

Multiple Choice

Q 70Q 70

What is the maximum value of the electric field E at 1.0 m from a 100-W light bulb radiating in all directions? (µ

_{0}= 4p * 10^{-7}Tm/A, c = 3.00 * 10^{8}m/s) A)77 V/m B)2 000 V/m C)4 000 V/m D)6 000 V/mFree

Multiple Choice

Q 71Q 71

Determine the amount of energy carried in l.0 m of a 3.5-mW He-Ne laser beam if the cross-sectional area of the beam is 5.0 * 10

^{-6}m^{2}. A)0.012 J B)4.1 * 10^{-}^{8}J C)1.2 * 10^{-}^{11}J D)1.0 JFree

Multiple Choice

Q 72Q 72

The Earth is 1.49 * 10

^{11 }m from the Sun.If the solar radiation at the top of the Earth's atmosphere is 1 340 W/m^{2}, what is the total power output of the Sun? A)7.48 * 10^{27}W B)2.34 * 10^{30}W C)6.62 * 10^{26}W D)3.74 * 10^{26 }WFree

Multiple Choice

Q 73Q 73

Peak values for a neodymium-glass laser are 600 J for 1 nanosecond.If the cross-section of the laser beam is 1 cm

^{2}, what are the maximum values of E and B? (µ_{0}= 4p * 10^{-7}Tm/A, c = 3.00 * 10^{8}m/s) A)2 * 10^{9}V/m, 2 T B)4 * 10^{8}V/m, 7 T C)2 * 10^{9}V/m, 7 T D)4 * 10^{8}V/m, 2 TFree

Multiple Choice

Q 74Q 74

A solar cell has a light-gathering area of 10 cm

^{2}and produces 0.20 A at 0.80 V (dc) when illuminated with sunlight of intensity 1 000 W/m^{2}.What is the efficiency of the solar cell? A)16% B)7% C)23% D)4%Free

Multiple Choice

Q 75Q 75

In order of increasing frequency, which of the following is correct?
A)visible, radio, ultraviolet and x-ray
B)infrared, visible, ultraviolet and gamma
C)visible, gamma, ultraviolet and x-ray
D)infrared, x-ray, visible and gamma

Free

Multiple Choice

Q 76Q 76

A radar pulse returns 3.0 * 10

^{-4}seconds after it is sent out, having been reflected by an object.What is the distance between the radar antenna and the object? (c = 3.00 * 10^{8}m/s) A)9.0 * 10^{4 }m B)4.5 * 10^{4}m C)6.0 * 10^{4}m D)1.0 * 10^{4}mFree

Multiple Choice

Q 77Q 77

In order to keep its food hot, a restaurant will place it under which type of lamp?
A)infrared
B)visible light
C)ultraviolet
D)x-ray

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Multiple Choice

Q 78Q 78

Glass panes are opaque to a certain type of radiation, which passes through quartz.What type of radiation is it? This radiation is important in ozone layer reactions.
A)microwave
B)gamma
C)x-ray
D)ultraviolet

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Multiple Choice

Q 79Q 79

A radio wave signal, which transmits at a frequency of 7.20 MHz, has what wavelength? (c = 3.00 * 10

^{8}m/s) A)41.7 m B)4.17 m C)28.8 m D)2.4 * 10^{-2}mFree

Multiple Choice

Q 80Q 80

A radar pulse sent out to an airplane at a distance of 20.0 km will return as an echo to the source in what time interval? (c = 3.00 * 10

^{8}m/s) A)33.3 * 10^{-6}s B)66.7 * 10^{-6}s C)133 * 10^{-6}s D)0.033 3 * 10^{-6}sFree

Multiple Choice

Q 81Q 81

The human eye is sensitive to light with wavelength down to 390 nm.What is the frequency of radiation at this wavelength? (1 nm = 10

^{-9}m and c = 3.00 * 10^{8}m/s) A)1.8 * 10^{8}Hz B)8.5 * 10^{8}Hz C)1.1 * 10^{11}Hz D)7.7 * 10^{14}HzFree

Multiple Choice

Q 82Q 82

An ultraviolet light wave has a wavelength of 300 nm and speed of 2.1 * 10

^{8 }m/s through a transparent medium.What is the frequency of this wave in the medium? (1 nm = 10^{-9}m and c = 3.00 * 10^{8}m/s) A)6.3 * 10^{2 }Hz B)9.0 * 10^{2}Hz C)7.0 * 10^{14}Hz D)10 * 10^{14 }HzFree

Multiple Choice

Q 83Q 83

Microwave radiation is useful in which of the following?
A)sending phone messages
B)cooking food
C)aircraft navigation
D)All of the above are valid choices.

Free

Multiple Choice

Q 84Q 84

Temperature variation of different parts of a person's body can be detected by analyzing the emission pattern of which type of electromagnetic radiation?
A)microwave
B)infrared
C)ultraviolet
D)x-rays

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Multiple Choice

Q 85Q 85

Of the various types of electromagnetic radiation, which is the most penetrating through all forms of matter?
A)infrared
B)gamma
C)visible light
D)ultraviolet

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Multiple Choice

Q 86Q 86

What value of inductance should be used in a series circuit with a capacitor of 1.8 * 10

^{-3}mF when designed to radiate a wavelength of 35 m? (c = 3.00 * 10^{8}m/s) A)3.8 mH B)2.6 * 10^{-2}mH C)3.8 * 10^{-3}mH D)1.9 * 10^{-4}mHFree

Multiple Choice

Q 87Q 87

As an electromagnetic wave travels through free space, its speed can be increased by:
A)increasing its frequency.
B)increasing its energy only.
C)increasing both its energy and momentum.
D)None of the above will increase its speed.

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Multiple Choice

Q 88Q 88

An object that is giving off only infrared electromagnetic waves is giving off heat through:
A)convection.
B)conduction.
C)radiation.
D)visible light.

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Multiple Choice

Q 89Q 89

The electromagnetic radiation that causes tanning:
A)can produce cancer.
B)rarely passes through glass windows.
C)is absorbed by ozone.
D)is all of the above.

Free

Multiple Choice

Q 90Q 90

What is the wavelength of 100-MHz television EM waves? (c = 3 * 10

^{8}m/s) A)0.3 cm B)3 m C)9 km D)10 mFree

Multiple Choice

Q 91Q 91

Find the frequency of x-rays of wavelength 10

^{-10 }m.(c = 3 * 10^{8}m/s) A)3 * 10^{18}Hz B)3 * 10^{16 }Hz C)6 * 10^{9}Hz D)3 * 10^{8}HzFree

Multiple Choice

Q 92Q 92

In the Doppler effect for electromagnetic waves, which of the following gives the greatest shift in frequency?
A)the source moving toward the non-moving observer at speed v
B)the observer moving toward the non-moving source at speed v
C)the source moving toward the approaching observer, both at speed v/2
D)All of the above give the same shift.

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Multiple Choice

Q 93Q 93

The Doppler shift for electromagnetic radiation from distant galaxies moving away from the observer is called a:
A)red shift.
B)blue shift.
C)black shift.
D)vacuum shift.

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Multiple Choice

Q 94Q 94

An observer is moving in space toward a distant star at 100 km/s while the star is moving toward the observer at 200 km/s; the relative velocity being 300 km/s of approach.What relative change in frequency of the light from the star as seen by the observer? (The speed of light in space is 3.00 * 10

^{5}km/s). A)0.10% increase B)0.10% decrease C)0.067% increase D)0.033% decreaseFree

Multiple Choice

Q 95Q 95

In an RLC circuit, the maximum current is 1 amp.What is the average current?
A) A
B) A
C)(1/2) A
D)None of the above.

Free

Multiple Choice

Q 96Q 96

In an RC circuit, which of the following is a possible phase angle?
A)45
B)-45
C)135
D)-135

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Multiple Choice

Q 97Q 97

In a 60-Hz RLC circuit, the phase angle is positive.The values of the resistance, inductance, and the capacitance are now doubled.Which of the following is now true about the phase angle?
A)It is still positive.
B)It could be zero.
C)It will be negative.
D)It could be positive, negative, or zero, but it cannot be greater than its original value.

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Multiple Choice

Q 98Q 98

A monochromatic light wave in vacuum has frequency f

_{0}and wavelength l_{0}.Which of the following are also possible frequency and wavelength combinations for a monochromatic light wave in vacuum? A)2f_{0}, 2l_{0}B)f_{0}/2, l_{0}/2 C)2f_{0}, l_{0}/2 D)None of the above are possible.Free

Multiple Choice

Q 99Q 99

An RLC circuit has resistance R

_{0}, inductance L_{0}, and capacitance C_{0}.If the resistance value is now doubled, which values of inductance and capacitance will result in the same resonant frequency as before. A)2L_{0}, 2C_{0}B)L_{0}/2, C_{0}/2 C)2L_{0}, C_{0}/2 D)2L_{0}, C_{0}Free

Multiple Choice