acdc ch 15, 16
T or F Impedance is measured in joules
F
T or F impedance aids the flow of alternating current.
F
A ________ change causes a change in inductive reactance.
Frequency
An ________ must be used to measure reactive power and true power in an AC circuit.
Power quality meter
Inductive ________ is the opposition of an inductor to alternating current.
Reactance
T or F The difference between true power and reactive power is that true power supplied to a resistive load is used to perform work or is dissipated as heat.
T
T or F Total current is equal to current flow through any component in a series resistive circuit
T
T or F Voltage at any given point during the rotation of a vector can be calculated by multiplying the sine of the vector rotation angle by the maximum peak voltage.
T
The value of average voltage is calculated to be equal to the instantaneous peak value multiplied by a factor of ___________
0.637
The common basis is that the effective value of 1 A of AC causes the same heating effect as ________ A of DC
1
Unity power factor is a power factor equal to ________
1
When a ratio of ________ to 1 exists between the inductive reactance and the resistance, the circuit is usually considered a pure inductive or pure resistive circuit, depending on which of the two is larger.
10
In an inductive AC circuit, CEMF is ________ degrees out of phase with the source voltage
180
In the generation of a sine wave, 0 V is induced into a rotating conductor at 0 degrees and at ________ Degrees
180
In a conductor rotating through 360 degrees, maximum positive voltage is inducted at ___________ Degrees rotation
90
Inductive current leads CEMF by ________ Degrees
90
In a pure resistive ________ circuit, the current sine wave and voltage sine wave are in phase with each other.
AC
Inductive reactance is affected by the size of the inductor and _________
AC frequency
The ability of a circuit containing both resistance and reactance to conductive current is known as _________
Admittance
The greater the ratio of inductive voltage drop to resistive voltage drop, the greater the ________ ________
Angle theta
T or F A peak to peak value measures from the maximum positive to the maximum negative alternation of a sine wave.
F
T or F Admittance is the phase difference between the source voltage and resistive voltage.
F
T or F An average value refers to a whole cycle of a sine wave.
F
T or F As frequency increases in a series inductive-resistive AC circuit, both impedance and current increase as well
F
T or F Current in an inductive AC circuit can be calculated without knowing source voltage
F
T or F Deflection of an electron beam in a CRT computer monitor is responsive to the average voltage.
F
T or F In a parallel inductive-resistive AC circuit, the algebraic sum of the two currents is equal to the source current.
F
T or F Peak power is equal to effective voltage multiplied by effective current.
F
T or F Power dissipated in a circuit is always negative
F
T or F Quality factor is measured in volt-amperes reactive.
F
T or F Resistances connected in series are subtracted from each other in an AC circuit
F
T or F The common value of voltage used in homes in the united states is 240 VAC
F
T or F The root-mean-square voltage value is also known as the mathematical factor for the peak value.
F
T or F The standard power source line frequency in Canada is 120 Hz
F
T or F The value of impedance is always less than that of reactance or resistance
F
T or F True power is measured in volt-amperes and apparent power is measured in watts
F
T or F When an AC value is given without it being specified, it is assumed to be a peak value
F
T or F inductors have no resistance
F
Power ________ is the ratio of true power to apparent power.
Factor
A ___________ is a selective network of resistances, capacitances, and inductances that provides little opposition to certain frequencies or DC while blocking or attenuating other frequencies.
Filter
________ capacitors are used to control harmonics problems in the power source.
Filter
Ripple voltage is output voltage of a power source harmonically related in ___________ to the power source.
Frequency
Under normal conditions, ________ does not change unless it is from a variable inductor
Inductance
________ changes directly in proportion with changes in either frequency or inductance
Inductive reactance
Power is positive and reaches its ________ value at 90 degrees and 270 degrees
Maximum
The average value of an AC voltage or current is the ___________ of all instantaneuos values in a sine wave
Mean
The ___________ value of an AC voltage or current refers to the maximum instantaneous value of the sine wave.
Peak
In a rectifier circuit, the diode is rated for the ________ voltage.
Peak to Peak
A voltage ________ is a vector diagram used to show the magnitude and phase of voltage in a series inductive-resistive AC circuit
Phasor
A ___________ curve is a graph that shows the changes in a circuit power as AC parameters change over time.
Power
The greater the frequency in a parallel inductive-resistive circuit, the greater the ________.
Power factor
________ factor is the ratio of the inductive reactance to the resistance of an inductor
Quality
In an inductive-resistive AC circuit, almost all of the power is ________ power.
Reactive
________ is power supplied to a reactive load.
Reactive power
No shift in the phase occurs between current and voltage in a ________ resistive AC circuit
Series
The unit of admittance is the ________
Siemen
________ is the reciprocal of the reactive component of impedance
Susceptance
_________ is the ability of a reactive circuit to conduct current and is measured in siemens.
Susceptance
T or F A pure inductive circuit is an AC circuit with no resistance
T
T or F Although there is little true power in a pure reactive circuit, there is still current in the circuit.
T
T or F An average DC current causes greater heat than an average AC current
T
T or F Apparent power represents a load that has both true power and reactive power
T
T or F Bleeder resistors reduce changes in the ripple voltage when current is delivered to the load.
T
T or F CEMF is created by a change in current, which is caused by a constantly changing magnetic field that cuts the inductor
T
T or F Current can be calculated in inductive AC circuits by modifying Ohm's law to substitute inductive reactance for resistance
T
T or F Frequency does not affect resistance in a parallel inductive-resistive AC circuit
T
T or F In a live circuit, it is not possible to separately measure inductive voltage and inductive resistance because the inductor is the resistive element.
T
T or F In an AC resistive circuit, instantaneous current and voltage are in phase while power is always a positive value.
T
T or F In inductive-resistive AC circuits, voltage is the same across all components connected in parallel
T
T or F Kirchhoff's voltage law states that the algebraic sum of the voltage in a closed-loop circuit is equal to zero
T
T or F Only resistance can dissipate power in an electrical circuit.
T
T or F When current flows through a diode, electrons are supplied by the positive plate of the capacitor and flow through the bleeder resistor.
T
T or F inductance can be held constant with the frequency varied, or frequency can be held constant with the inductance varied
T
T or F poor power factor exists when the power factor in a circuit is less than 90%
T
________ power in an inductive-resistive AC circuit is converted to heat in the inductor due to the resistance of the inductor
True
Under normal conditions in power circuits, ________ power factor is the most desirable condition
Unity
Reactive power is measured in ________.
Volt amperes
When analyzing an inductive-resistive circuit, ________ are used to calculate the effective voltage and phase difference between the inductive and resistive voltages.
Voltage phasors
True power is measured in ________.
Watts
In series resistive AC circuits, ___________ is used as the reference for all circuit parameters.
current
Inductance opposes any change in ________
current
The ___________ value of AC voltage is the value of a sine wave that produces the same amount of heat as DC of the same value.
effective
Impedance in an AC circuit can be found in the form of capacitave reactance or ________ reactance
inductive
In a parallel resistive AC circuit, the ___________ is the same across all components and devices.
voltage
in a series resistive AC circuit, true power is equal to ________
Apparent Power
When the ___________ value is used, it relates to the value of one alternation, or half-cycle, of a sine wave.
Average
A ___________ is used to protect equipment from excessive voltages if the load is removed or substantially reduced.
Bleeder resistor
Bleeder resistors are used to bleed resisdual charges off of an ___________ when the power source is turned off.
Capacitor
________ is used to calculate most parameters in a parallel inductive-resistive circuit
Current