.
Extra Class Study Guide E2
SUBELEMENT E5 -- ELECTRICAL PRINCIPLES [4 Exam Questions -- 4 Groups]
E5A Resonance and Q: characteristics of resonant circuits: series and parallel resonance; Q; half-power bandwidth; phase relationships in reactive circuits
E5A01
What can cause the voltage across reactances in series to be larger than the voltage applied to them
A. Resonance
B. Capacitance
C. Conductance
D. Resistance
E5A02
What is resonance in an electrical circuit
A. The highest frequency that will pass current
B. The lowest frequency that will pass current
C. The frequency at which the capacitive reactance equals the inductive reactance
D. The frequency at which the reactive impedance equals the resistive impedance
E5A03
What is the magnitude of the impedance of a series R-L-C circuit at resonance
A. High, as compared to the circuit resistance
B. Approximately equal to capacitive reactance
C. Approximately equal to inductive reactance
D. Approximately equal to circuit resistance
E5A04
What is the magnitude of the impedance of a circuit with a resistor, an inductor and a capacitor all in parallel, at resonance
A. Approximately equal to circuit resistance
B. Approximately equal to inductive reactance
C. Low, as compared to the circuit resistance
D. Approximately equal to capacitive reactance
E5A05
What is the magnitude of the current at the input of a series R-L-C circuit as the frequency goes through resonance
A. Minimum
B. Maximum
C. R/L
D. L/R
E5A06 (Was E5A08; edited]
What is the magnitude of the circulating current within the components of a parallel L-C circuit at resonance
A. It is at a minimum
B. It is at a maximum
C. It equals 1 divided by the quantity [ 2 multiplied by Pi, multiplied by the square root of ( inductance "L" multiplied by capacitance "C" )]
D. It equals 2 multiplied by Pi, multiplied by frequency "F", multiplied by inductance "L"
E5A07
What is the magnitude of the current at the input of a parallel R-L-C circuit at resonance
A. Minimum
B. Maximum
C. R/L
D. L/R
E5A08
What is the phase relationship between the current through and the voltage across a series resonant circuit
A. The voltage leads the current by 90 degrees
B. The current leads the voltage by 90 degrees
C. The voltage and current are in phase
D. The voltage and current are 180 degrees out of phase
E5A09
What is the phase relationship between the current through and the voltage across a parallel resonant circuit
A. The voltage leads the current by 90 degrees
B. The current leads the voltage by 90 degrees
C. The voltage and current are in phase
D. The voltage and current are 180 degrees out of phase
E5A10
What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 1.8 MHz and a Q of 95
A. 18.9 kHz
B. 1.89 kHz
C. 94.5 kHz
D. 9.45 kHz
E5A11
What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 7.1 MHz and a Q of 150
A. 157.8 Hz
B. 315.6 Hz
C. 47.3 kHz
D. 23.67 kHz
E5A12
What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 3.7 MHz and a Q of 118
A. 436.6 kHz
B. 218.3 kHz
C. 31.4 kHz
D. 15.7 kHz
E5A13
What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 14.25 MHz and a Q of 187
A. 38.1 kHz
B. 76.2 kHz
C. 1.332 kHz
D. 2.665 kHz
E5A14
What is the resonant frequency of a series RLC circuit if R is 22 ohms, L is 50 microhenrys and C is 40 picofarads
A. 44.72 MHz
B. 22.36 MHz
C. 3.56 MHz
D. 1.78 MHz
E5A15
What is the resonant frequency of a series RLC circuit if R is 56 ohms, L is 40 microhenrys and C is 200 picofarads
A. 3.76 MHz
B. 1.78 MHz
C. 11.18 MHz
D. 22.36 MHz
E5A16
What is the resonant frequency of a parallel RLC circuit if R is 33 ohms, L is 50 microhenrys and C is 10 picofarads
A. 23.5 MHz
B. 23.5 kHz
C. 7.12 kHz
D. 7.12 MHz
E5A17
What is the resonant frequency of a parallel RLC circuit if R is 47 ohms, L is 25 microhenrys and C is 10 picofarads
A. 10.1 MHz
B. 63.2 MHz
C. 10.1 kHz
D. 63.2 kHz
E5B Time constants and phase relationships: R/L/C time constants: definition; time constants in RL and RC circuits; phase angle between voltage and current; phase angles of series and parallel circuits
E5B01
What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the supply voltage
A. An exponential rate of one
B. One time constant
C. One exponential period
D. A time factor of one
E5B02
What is the term for the time it takes for a charged capacitor in an RC circuit to discharge to 36.8% of its initial value of stored charge
A. One discharge period
B. An exponential discharge rate of one
C. A discharge factor of one
D. One time constant
E5B03
The capacitor in an RC circuit is discharged to what percentage of the starting voltage after two time constants
A. 86.5%
B. 63.2%
C. 36.8%
D. 13.5%
E5B04
What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in parallel
A. 55 seconds
B. 110 seconds
C. 440 seconds
D. 220 seconds
E5B05
How long does it take for an initial charge of 20 V DC to decrease to 7.36 V DC in a 0.01-microfarad capacitor when a 2-megohm resistor is connected across it
A. 0.02 seconds
B. 0.04 seconds
C. 20 seconds
D. 40 seconds
E5B06
How long does it take for an initial charge of 800 V DC to decrease to 294 V DC in a 450-microfarad capacitor when a 1-megohm resistor is connected across it
A. 4.50 seconds
B. 9 seconds
C. 450 seconds
D. 900 seconds
E5B07
What is the phase angle between the voltage across and the current through a series R-L-C circuit if XC is 500 ohms, R is 1 kilohm, and XL is 250 ohms
A. 68.2 degrees with the voltage leading the current
B. 14.0 degrees with the voltage leading the current
C. 14.0 degrees with the voltage lagging the current
D. 68.2 degrees with the voltage lagging the current
E5B08
What is the phase angle between the voltage across and the current through a series R-L-C circuit if XC is 100 ohms, R is 100 ohms, and XL is 75 ohms
A. 14 degrees with the voltage lagging the current
B. 14 degrees with the voltage leading the current
C. 76 degrees with the voltage leading the current
D. 76 degrees with the voltage lagging the current
E5B09 was E5D06
What is the relationship between the current through and the voltage across a capacitor
A. Voltage and current are in phase
B. Voltage and current are 180 degrees out of phase
C. Voltage leads current by 90 degrees
D. Current leads voltage by 90 degrees
E5B10 was E5D07
What is the relationship between the current through an inductor and the voltage across an inductor
A. Voltage leads current by 90 degrees
B. Current leads voltage by 90 degrees
C. Voltage and current are 180 degrees out of phase
D. Voltage and current are in phase
E5B11 was E5D08
What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 25 ohms, R is 100 ohms, and XL is 50 ohms
A. 14 degrees with the voltage lagging the current
B. 14 degrees with the voltage leading the current
C. 76 degrees with the voltage lagging the current
D. 76 degrees with the voltage leading the current
E5B12 was E5D10
What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 75 ohms, R is 100 ohms, and XL is 50 ohms
A. 76 degrees with the voltage lagging the current
B. 14 degrees with the voltage leading the current
C. 14 degrees with the voltage lagging the current
D. 76 degrees with the voltage leading the current
E5B13 was E5D11
What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 250 ohms, R is 1 kilohm, and XL is 500 ohms
A. 81.47 degrees with the voltage lagging the current
B. 81.47 degrees with the voltage leading the current
C. 14.04 degrees with the voltage lagging the current
D. 14.04 degrees with the voltage leading the current
E5C Impedance plots and coordinate systems: plotting impedances in polar coordinates; rectangular coordinates
E5C01
In polar coordinates, what is the impedance of a network consisting of a 100-ohm-reactance inductor in series with a 100-ohm resistor
A. 121 ohms at an angle of 35 degrees
B. 141 ohms at an angle of 45 degrees
C. 161 ohms at an angle of 55 degrees
D. 181 ohms at an angle of 65 degrees
E5C02
In polar coordinates, what is the impedance of a network consisting of a 100-ohm-reactance inductor, a 100-ohm-reactance capacitor, and a 100-ohm resistor, all connected in series
A. 100 ohms at an angle of 90 degrees
B. 10 ohms at an angle of 0 degrees
C. 10 ohms at an angle of 90 degrees
D. 100 ohms at an angle of 0 degrees
E5C03
In polar coordinates, what is the impedance of a network consisting of a 300-ohm-reactance capacitor, a 600-ohm-reactance inductor, and a 400-ohm resistor, all connected in series
A. 500 ohms at an angle of 37 degrees
B. 900 ohms at an angle of 53 degrees
C. 400 ohms at an angle of 0 degrees
D. 1300 ohms at an angle of 180 degrees
E5C04
In polar coordinates, what is the impedance of a network consisting of a 400-ohm-reactance capacitor in series with a 300-ohm resistor
A. 240 ohms at an angle of 36.9 degrees
B. 240 ohms at an angle of -36.9 degrees
C. 500 ohms at an angle of 53.1 degrees
D. 500 ohms at an angle of -53.1 degrees
E5C05
In polar coordinates, what is the impedance of a network consisting of a 400-ohm-reactance inductor in parallel with a 300-ohm resistor
A. 240 ohms at an angle of 36.9 degrees
B. 240 ohms at an angle of -36.9 degrees
C. 500 ohms at an angle of 53.1 degrees
D. 500 ohms at an angle of -53.1 degrees
E5C06
In polar coordinates, what is the impedance of a network consisting of a 100-ohm-reactance capacitor in series with a 100-ohm resistor
A. 121 ohms at an angle of -25 degrees
B. 191 ohms at an angle of -85 degrees
C. 161 ohms at an angle of -65 degrees
D. 141 ohms at an angle of -45 degrees
E5C07
In polar coordinates, what is the impedance of a network comprised of a 100-ohm-reactance capacitor in parallel with a 100-ohm resistor
A. 31 ohms at an angle of -15 degrees
B. 51 ohms at an angle of -25 degrees
C. 71 ohms at an angle of -45 degrees
D. 91 ohms at an angle of -65 degrees
E5C08
In polar coordinates, what is the impedance of a network comprised of a 300-ohm-reactance inductor in series with a 400-ohm resistor
A. 400 ohms at an angle of 27 degrees
B. 500 ohms at an angle of 37 degrees
C. 500 ohms at an angle of 47 degrees
D. 700 ohms at an angle of 57 degrees
E5C09
When using rectangular coordinates to graph the impedance of a circuit, what does the horizontal axis represent
A. The voltage or current associated with the resistive component
B. The voltage or current associated with the reactive component
C. The sum of the reactive and resistive components
D. The difference between the resistive and reactive components
E5C10
When using rectangular coordinates to graph the impedance of a circuit, what does the vertical axis represent
A. The voltage or current associated with the resistive component
B. The voltage or current associated with the reactive component
C. The sum of the reactive and resistive components
D. The difference between the resistive and reactive components
E5C11
What do the two numbers represent that are used to define a point on a graph using rectangular coordinates
A. The magnitude and phase of the point
B. The sine and cosine values
C. The coordinate values along the horizontal and vertical axes
D. The tangent and cotangent values
E5C12
If you plot the impedance of a circuit using the rectangular coordinate system and find the impedance point falls on the right side of the graph on the horizontal line, what do you know about the circuit
A. It has to be a direct current circuit
B. It contains resistance and capacitive reactance
C. It contains resistance and inductive reactance
D. It is equivalent to a pure resistance
E5C13
What coordinate system is often used to display the resistive, inductive, and/or capacitive reactance components of an impedance
A. Maidenhead grid
B. Faraday grid
C. Elliptical coordinates
D. Rectangular coordinates
E5C14
What coordinate system is often used to display the phase angle of a circuit containing resistance, inductive and/or capacitive reactance
A. Maidenhead grid
B. Faraday grid
C. Elliptical coordinates
D. Polar coordinates
E5C15
In polar coordinates, what is the impedance of a circuit of 100 -j100 ohms impedance
A. 141 ohms at an angle of -45 degrees
B. 100 ohms at an angle of 45 degrees
C. 100 ohms at an angle of -45 degrees
D. 141 ohms at an angle of 45 degrees
E5C16
In polar coordinates, what is the impedance of a circuit that has an admittance of 7.09 millisiemens at 45 degrees
A. 5.03 x 10 –E05 ohms at an angle of 45 degrees
B. 141 ohms at an angle of -45 degrees
C. 19,900 ohms at an angle of -45 degrees
D. 141 ohms at an angle of 45 degrees
E5C17
In rectangular coordinates, what is the impedance of a circuit that has an admittance of 5 millisiemens at -30 degrees
A. 173 - j100 ohms
B. 200 + j100 ohms
C. 173 + j100 ohms
D. 200 - j100 ohms
E5C18
In polar coordinates, what is the impedance of a series circuit consisting of a resistance of 4 ohms, an inductive reactance of 4 ohms, and a capacitive reactance of 1 ohm
A. 6.4 ohms at an angle of 53 degrees
B. 5 ohms at an angle of 37 degrees
C. 5 ohms at an angle of 45 degrees
D. 10 ohms at an angle of -51 degrees
E5C19
Which point on Figure E5-2 best represents that impedance of a series circuit consisting of a 400 ohm resistor and a 38 picofarad capacitor at 14 MHz
A. Point 2
B. Point 4
C. Point 5
D. Point 6
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E5C20
Which point in Figure E5-2 best represents the impedance of a series circuit consisting of a 300 ohm resistor and an 18 microhenry inductor at 3.505 MHz
A. Point 1
B. Point 3
C. Point 7
D. Point 8
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E5C21
Which point on Figure E5-2 best represents the impedance of a series circuit consisting of a 300 ohm resistor and a 19 picofarad capacitor at 21.200 MHz
A. Point 1
B. Point 3
C. Point 7
D. Point 8
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E5C22
In rectangular coordinates, what is the impedance of a network comprised of a 10-microhenry inductor in series with a 40-ohm resistor at 500 MHz
A. 40 + j31,400
B. 40 - j31,400
C. 31,400 + j40
D. 31,400 - j40
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E5C23
Which point on Figure E5-2 best represents the impedance of a series circuit consisting of a 300-ohm resistor, a 0.64-microhenry inductor and an 85-picofarad capacitor at 24.900 MHz
A. Point 1
B. Point 3
C. Point 5
D. Point 8
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E5D AC and RF energy in real circuits: skin effect; electrostatic and electromagnetic fields; reactive power; power factor; coordinate systems
E5D01
What is the result of skin effect
A. As frequency increases, RF current flows in a thinner layer of the conductor, closer to the surface
B. As frequency decreases, RF current flows in a thinner layer of the conductor, closer to the surface
C. Thermal effects on the surface of the conductor increase the impedance
D. Thermal effects on the surface of the conductor decrease the impedance
E5D02
Why is the resistance of a conductor different for RF currents than for direct currents
A. Because the insulation conducts current at high frequencies
B. Because of the Heisenburg Effect
C. Because of skin effect
D. Because conductors are non-linear devices
E5D03
What device is used to store electrical energy in an electrostatic field
A. A battery
B. A transformer
C. A capacitor
D. An inductor
E5D04
What unit measures electrical energy stored in an electrostatic field
A. Coulomb
B. Joule
C. Watt
D. Volt
E5D05
What is a magnetic field
A. Electric current through the space around a permanent magnet
B. The region surrounding a magnet through which a magnetic force acts
C. The space between the plates of a charged capacitor, through which a magnetic force acts
D. The force that drives current through a resistor
E5D06
In what direction is the magnetic field oriented about a conductor in relation to the direction of electron flow
A. In the same direction as the current
B. In a direction opposite to the current
C. In all directions; omnidirectional
D. In a direction determined by the left-hand rule
E5D07
What determines the strength of a magnetic field around a conductor
A. The resistance divided by the current
B. The ratio of the current to the resistance
C. The diameter of the conductor
D. The amount of current
E5D08
What is the term for energy that is stored in an electromagnetic or electrostatic field
A. Amperes-joules
B. Potential energy
C. Joules-coulombs
D. Kinetic energy
E5D09
What is the term for an out-of-phase, nonproductive power associated with inductors and capacitors
A. Effective power
B. True power
C. Peak envelope power
D. Reactive power
E5D10
In a circuit that has both inductors and capacitors, what happens to reactive power
A. It is dissipated as heat in the circuit
B. It is repeatedly exchanged between the associated magnetic and electric fields, but is not dissipated
C. It is dissipated as kinetic energy in the circuit
D. It is dissipated in the formation of inductive and capacitive fields
E5D11
How can the true power be determined in an AC circuit where the voltage and current are out of phase
A. By multiplying the apparent power times the power factor
B. By dividing the reactive power by the power factor
C. By dividing the apparent power by the power factor
D. By multiplying the reactive power times the power factor
E5D12
What is the power factor of an R-L circuit having a 60 degree phase angle between the voltage and the current
A. 1.414
B. 0.866
C. 0.5
D. 1.73
E5D13
How many watts are consumed in a circuit having a power factor of 0.2 if the input is 100-V AC at 4 amperes
A. 400 watts
B. 80 watts
C. 2000 watts
D. 50 watts
E5D14
How much power is consumed in a circuit consisting of a 100 ohm resistor in series with a 100 ohm inductive reactance drawing 1 ampere
A. 70.7 Watts
B. 100 Watts
C. 141.4 Watts
D. 200 Watts
E5D15
What is reactive power
A. Wattless, nonproductive power
B. Power consumed in wire resistance in an inductor
C. Power lost because of capacitor leakage
D. Power consumed in circuit Q
E5D16
What is the power factor of an RL circuit having a 45 degree phase angle between the voltage and the current
A. 0.866
B. 1.0
C. 0.5
D. 0.707
E5D17 was [E5H14]
What is the power factor of an RL circuit having a 30 degree phase angle between the voltage and the current
A. 1.73
B. 0.5
C. 0.866
D. 0.577
E5D18
How many watts are consumed in a circuit having a power factor of 0.6 if the input is 200V AC at 5 amperes
A. 200 watts
B. 1000 watts
C. 1600 watts
D. 600 watts
E5D19
How many watts are consumed in a circuit having a power factor of 0.71 if the apparent power is 500 watts
A. 704 W
B. 355 W
C. 252 W
D. 1.42 mW