AC Final
A capacitor is considered fully charged after how many time constants?
5
Unity power factor is a power factor equal to
1
In a conductor rotating 360 degrees through a magnetic field, maximum voltage is induced as ______ degrees and 270 degrees rotation
90
Inductive current leads CEMF by ______ degrees
90
In a pure capacitive circuit, current leads the source voltage by
90 degrees
If an AC waveform is rectified and converted into DC, the voltage value that results is the
Average Value
The unit of inductance equal to the voltage induced per rate of current change
Henry
Unit of measurement for inductance
Henry
Unit of frequency
Hertz
Dividing source voltage by the total circuit current yields __________ in a resistive-capacitive circuit
Impedance
The total opposition to current in a circuit that contains inductance, capacitance, and resistance
Impedance
The percentage of magnetic lines of force created by one coil that cut the windings of the second coil
Coefficient of Coupling
A change in ________ causes a change in inductive reactance
Frequency
The number of cycles completed in one second is called?
Frequency
The thicker the dielectric, the __________ the voltage it can withstand
Greater
The value of impedance is always ___________ than that of reactance or resistance
Greater
The difference between true power and reactive power is that ______________ supplied to a resistive load is used to perform work or is dissipated as heat
True Power
The unit of measure for power of a resistor in an AC circuit
True Power
When the values of source voltage and total current are known, _______ in a series resistive-capacitive circuit can be calculated by multiplying the voltage and current
True Power
A solenoid is an electric output device that converts electrical energy into
Linear Mechanical Force
Sometimes referred to as glass capacitors
Mica Capacitors
Inductor usually covered in plastic with a conductor at each end for connecting or soldering into a circuit
Molded inductor
Is the effect of one coil inducing a voltage into another coil
Mutual Inductance
An inductor that has coils wound in such a manner that the inductance created by one coil turn is cancelled by an adjacent coil turn
Non inductive coil
Can be used in AC and DC circuits
Non-Polarized
Capacitive Reactance is measured in?
Ohms
The most commonly used capacitors used for motor start capacitors are
Oil filled Capacitors
New digital multimeters, will read the _______ voltage of an AC sine wave
RMS
The square root of the mean of the square of the instantaneous currents is the?
RMS
Inductive _____________ is the opposition of an inductor to current in an AC current
Reactance
In an inductive-resistive AC circuit, the power of the inductor is ____________ power
Reactive
Current can be calculated in inductive AC circuits by modifying Ohm's law to substitute inductive reactance (XL) for
Resistance
Only ___________ can dissipate power in an electrical circuit
Resistance
The _______ effect occurs when AC induces eddy currents into the conductor, which cause the electrons to be repelled toward the outer surface of the conductor
Skin
Dielectric ___________ strength is the amount of voltage a dielectric material can safely handle
Strength
A ________ can be used as a battery replacement because it has characteristics similar to those of a battery
Super Capacitor
Formula to find one time constant for an inductor?
T=L/R
Also called Wattless power where no work is performed
VAR's
Reactive power is measured in
VAR's
Usually use air as the dielectric
Variable Capacitors
An inductor that consists of two coils, one fixed and one moveable
Variometer
In a parallel resistive AC circuit, the _________ is used as the reference for all circuit parameters
Voltage
In a series/parallel resistive-capacitive circuit, _________ is used as the reference point for all components and devices
Voltage
Average voltage equals peak voltage times
.637
RMS voltage equals peak voltage times
.707
In the generation of a sine wave, 0 volts is induced into a rotating conductor at ______ degrees and 180 degrees rotaion
0
Capacitance of a circuit is affected by
1. Dielectric constant of the material 2. Surface area of the plates 3. Thickness of the material
RMS voltage equals average voltage times
1.1
In an inductive AC circuit, CEMF is ________ degrees out of phase with the source voltage
180
Maximum out-of-phase condition occurs when signals are _____ degrees out of phase
180
Inductive reactance is affected by the size of the inductor in Henry's and?
AC frequency
Half-cycle of a sine wave, either positive or negative
Alternation
The greater the ratio of inductive voltage drop to resistive voltage drop, the greater the
Angle theta
In a series resistive AC circuit, true power is equal to ____________ power or VA
Apparent
Opposition to electron flow by a capacitor
Capacitive Reactance
When frequency is changed, the only parameter directly affected is the ___________, while the other parameters are indirectly affected by the change
Capacitive Reactance
Dielectric ____________ is the ratio of the capacitance of a capacitor with a given dielectric to the capacitance of a capacitor with air as the dielectric
Constant
If angle theta and power in Watt's is known, the ________ function can be used to calculate the value of the source apparent power
Cosine
Power factor is equal to the ___________ of angle theta
Cosine
CEMF is created by a change in ___________, which is caused by a constantly changing magnetic field that cuts the windings of an inductor
Current
In a power resistive circuit, the voltage sine wave and _________ sine waves are in phase with each other in both the positive and negative alternations
Current
In a series resistive-capacitive circuit __________ is the same at all points for all components and devices
Current
Inductance opposes any change in
Current
_______ is used as the reference for all circuit parameters in a series resistive AC circuit
Current
Each complete waveform of 360 degrees is called?
Cycle
Inductance is affected by
Diameter, Shape, and Material
The breakdown of insulation between the plates of a capacitor
Dielectric Breakdown
A term used to indicate the same value as the RMS value is the _________ value
Effective
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
In a capacitive circuit, __________ only when a capacitor is charging or discharging
Electrons Flow
Capacitors can be connected together in parallel so that their capacitance?
Increases
Abrupt removal of power from a circuit often causes coils to fail because of
Inductive kick
Opposes a change of current
Inductor
Passive device that stores energy in the form of a magnetic field
Inductor
The ________ value of AC voltage equals the sine of the angle rotation times the peak voltage value
Instantaneous
Capacitive reactance is ____________ proportional to frequency
Inversely
Capacitive voltage _________ source voltage at all times in a capacitor only closed-loop circuit
Is equal to the
The small amount of current that flows through insulation
Leakage Current
A _________ capacitor has thin sheets of metallic foil, which act as plates, seperated by waxed paper which acts as the dielectric
Paper
An electrolyte in a capacitor can be in the form of a liquid or?
Paste
The____ value of AC voltage is the voltage from base to the maximum voltage
Peak-to-Peak
Has separate negative and positive connection leads
Polarised Capacitor
A _______ curve is a graph that shows the changes in circuit power as AC parameters, voltage, and current change over time
Power
In an AC system _________ is used as the reference for all circuit parameters
Power
The ratio of true power to apparent power
Power Factor
A __________ must be used to measure reactive power and true power in an AC circuit
Power Quality Meter
Time curve for current in an inductive-resistive circuit
Power curve
Inductive circuit has both resistance and inductance
Practical
When AC voltage is rectified and converted into DC, the resulting waveform is normally not pure, flat DC. The pulses that occur are called?
Ripples
AC voltage is most commonly made by
Rotating Machines
The property of a conductor to induce voltage within itself due to changes in current
Self Induction
The time required for current in an inductive-resistive circuit to reach 63.2% of its maximum value after power is applied
Time Constant
Time required to produce one complete cycle of a waveform
Time Period
A resistive-capacitive ______ is the amount of time required for the capacitor to charge to 63.2% of the maximum voltage across the circuit
Time constant
It takes 5 _________ for current to reach its maximum value in a LR circuit
Time constants
What type of coils are used for current transformers?
Toroid Coils
Electrical devices that use electromagnetism to step up or down voltage from one level to another and make AC more practical than DC
Transformers
Under normal conditions in power circuits, _________ power factor, a power factor of 100%, is the most desirable condition
Unity
True power is measured in
Watts
The distance covered by one complete cycle of a given frequency of sound as it passes through the air
Wavelength
