5-2 AC Theory Final Practice Test
AC motors were invented by ---- who was an inventor, mechanical engineer, and electrical engineer.
Nikola Tesla
The series RC circuit is similar to the ---- circuit in that it uses the circuit current as the reference.
RL
The -----is a type of instrument that is used to determine the phase relationship between two separate generator voltages.
Synchoroscope
recharging of a battery is an example of ----
chemical action
One variation of a --- circuit is the series circuits in parallel with each other
combination
The power factor of a circuit is the --- of the phase angle
cosine
Induced voltage produces a ----
current
in the right-hand rule for motors, the ---- finger on the right hand represents flux direction of the field.
first
in a ---- capacitor, the capacitance is determined by the manufacturer and parameters set.
fixed
This sine wave generation is called the --- effect on an LC tank circuit
flywheel
The opposition offered to an AC current will be expressed in the --- of the coil.
impedance (Z)
the total --- is always calculated by adding the vectors or by using the Pythagorean theorem
impedance (Z)
If the frequency is increased above the reasonant frequency, the inductive reactance ----
increases.
to find the voltage drop across circuit components, use the line current x the ---- oppositions
individual
The term ---- simply means the rotors have voltage induced into them.
induction motor
In a parallel RLC circuit, if the inductance is large, so is the Xl, causing a comparatively small amount of current to flow throught the ---- branch
inductive
The six methods kown to force electrons from the valence ring of an atom to become a ptential electricla current are friction, chemical, heat, pressure, magnetism, and ----
light
As the rotor spins within the stator of the motor, it creates the --- poles on the rotor.
magnetic
The ability of a material to allow or conduct magnetic lines of flux is known as-----
magnetic permeability
the ability of a material to concentrate or focus magnetic flux lines is called----
permeability
We can predict how a coil will react to a current based on its ---
physical properties.
As the AC supply voltage reverses ---, the stored energy in the inductor's magnetic field and capacitor's electrostatic field charge and discharge within the tank.
polarity
As an ---- receives current from the source, it creates a flux based on the applied voltage and the number or turn or wire
primary winding
atoms have three main parts:----
protons, neutrons, electrons
The circuit may change from a leading to a lagging power factor depending on the changing values of inductive and capacitive ---- in the circuit
reactance
The impedance of the parallel circuit is the ---- of the sum of the reciprocals of the branches.
reciprocal
The items needed to generate voltage are a conductor, and magnetic field, and ----- between the conductor and the magnetic field
relative motion
continues bands of metal install around a shaft, connected to the rotating windings of an AC generator, slip rings and designed to connect the AC output directly to the load are known as-----
slip rings
when an AC circuit has the elements of resistance, inductance, and capacitive reactance connected in parallel, the voltage drop across each branch is----
the same as it is in any parallel circuit
The current in all elements of the series circuit is equal to the ---- current.
total
Magnet wire has a coating of insulating varnish that provides the --- rating for the wire
voltage
The main purpose of most transformers is to transfer energy while changing the ---- level of the circuit between primary and secondary
voltage
a circuit is more inductive than capacitive, the current will lag the applied----
voltage
True power is measured in ----- and it is represented or shown along the horizontal axis because it has a zero degree angle.
watts
The --- is used to determine the compatibility of Transformer paralleling and to calculate the secondary fault current if a short occurs in the secondary.
% impedance
If you use the sine of the angle of movement and multiply it by the expected maximum voltage then the resultant is plotted on a graph, and for each of the 360 degrees of rotation you will see a figure known as --- sine wave
AC
In all AC circuits, the PF is a factor applied to the ---- of the circuit.
Apparent power
--- ride on the commutator to connect the rotating armature to the load.
Brushes
When ordering an installing capacitors for power factor correction, capacitors are specified in ---- and with the rated voltage to be connected.
C-VAR (Capacitive Kilo Volts-amps Reactive)
---- have voltage electrically connected to the rotor.
Conduction motors
A formula allows us to produce a coil that has a certain amount of inductance, which is measured in ----
Henries
The unit of measure for inductance is known as a ---
Henry
----- is the opposition to a changing magnetic field within a magnetized material.
Hysteresis
The formula ----, using Xl or Xc for R, will allow us to determine the power whether true or reactive for each component in a combination RLC circuit.
I^2xR=P
---- induction is the correct heuristic that allows us to use Transformers.
Mutual
The amount of current flow through the inductor is calculated using the adapted --- law formula.
Ohm's
---- is a multiple (factor) applies to the apparent power to yield true power.
Power factor
In a combination RLC circuit, the sum of the vertical components can be added to the sum of the horizontal components using the ---- Theorem
Pythagorem
Load circuits themselves are usually primarily either --- in series and are connected in parallel between the supply wires.
R o RL
A circuit that contains resistance and capacitance is called a --- circuit.
RC
A parallel circuit that contains reistance and capacitance is called an ---- circuit.
RC
The ---- value is also called the effective value
RMS
sometimes they slip is just expressed as a ---
RPM
Horizontal and vertical components for current vectors of known mete reading are added together to determine ---
Unknown values
The power factor is calculated by dividing the true power (W) of the circuit by the ----
VA apparent power
The unit of electrical power is the ---
Watt (W)
the effects of frequency on a series RC circuit can be analyzed by determining what happens to the --- of a capacitor
Xc
The total circuit impedance can be found using any of the total values and substituting - - - for opposition in the Omh's law formula
Z impedance
if we were to vector a circuit with resistors are added in parallel, the process would be to --- all the current vectors, at the same angle, together to find the total circuit current.
add
Opposition vectors that are at the same angle and direction can be ---- together
added
In a combination RLC circuit, series vectors must be reduced to their vertical and horizontal components, which can then be vectorially -----
added together
When the capacitors are connected in parallel, the areas of the individual plates are ----
added together.
----is there primary source of electrical power
magnetism
The power triangle is made of vectors for watts, --- , and VARs of capacitive power.
volts amps
The power rating of a transformer is rated in --- because the transformer is designed to transform voltage and current and has no influence on how tht power is used.
volts-amps
Special circuits that will allow current or voltage at certain frequencies to pass to the load, while at other frequencies, current and voltage are filtered out and do not appear at the load are called filters or ---
wave traps
Because inductive reactance and capacitive reactance substract from each other in an AC circuit, this subtraction may mean a total reactance that could be --- ohms.
zero (0)
the total impedance of a circuit is determined by the resistance at --- degrees to the horizontal, the Xl at 90° lagging, and the XC at 90° leading vectors.
0
In a series RC circuit, the voltage is always drawn as the reference at --- degrees on the horizontal.
0 (zero)
Initially when a capacitor is empty of charge it has --- volts across it.
0 (zero)
all currents there are in face with the line voltage are also reference to the --- axis
0-degree
In a parallel circuit, the inductive current and capacitive current are ---- degrees out of phase and subtract from each other
180
since inductive reactance and capacitive reactance are ---degrees out of phase with each other, they substract from each other in an AC circuit
180
find the Henry value of an inductor with the following dimensions: the number of turns on the coil of wire is 100 coma the area of the quarry in the middle of the coil is 3 square inches, the permeability of the iron core is 150, and the length of the core is 5 in.
28.7 millihernries
If a pure capacitive load (no resistance) is connected in an AC circuit, the voltage and current are --- degrees out of phase with each other.
90
the ohimc value is actually due to the voltage developed by the capacitor charge and creates a value that is --- degrees out of face with the resistance.
90
Generation of --- is the most widely used form of production of electricity.
AC
the formula used to determine the capacitance with the dielectric constant (k), the area of the plates (a)(in square inches), and the distance between the plates (d) (in inches) is----
C=KA/d
--- opposes a change in voltage by creating a current flow that opposes the change in voltage.
Capacitance
---- reactance is the opposition to the current flow in an AC circuit caused by the reaction of the capacitor.
Capacitive
---- or RC filtering is also used then the DC must be 'filtered out' or blocked and the A part of the amplified voltage is allowed to pass.
Capacitive coupling
..... is calculated by the adjacent side divided by the hypotenuse or Watts divided by VA
Cosine
To charge a capacitor, you connect it to a(n) ----- power.
DC
We can use the formula of --- to yield true power in an AC circuit.
E x I x power factor
The formula to find the voltage drop across Z1 and Z2 is ---
E=It x ZEquiv
----- is an invisible fource that can produce heat, motion, light, and any number of other physical effects
Electricity
capacitance is measured in
Farads (F)
There are three basics classifications of magnetic materials: ----
Ferromagnetic, paramagnetic, and diamagnetic.
The original capacitor was known as----jar
Leyden
You will find that if the two coils are aidng each other, the magnetic field becomes stronger in the total---- increases.
Lt ( Inductance)
---- energy delivered from raw manpower, water, wjnd, fossil fuels (coal and oil), and nuclear reactors is used to turn the rotors of a generator.
Mechanical
---- filters can be installed to prevent interference such as static or a low hum.
Power line
---- generators that get their name from the field windings being wired in parallel with or shunted across the generator output.
Shunt
--- transformers transform one sine wave of one voltage source at the input to another single sine wave of a new voltage source at the output
Single-phase
the calculations needed for transformer applications are basic - - - equations.
algebraic
The rate of change of----- per second of the changing current will determine the amount of CEMF.
amps
The --- is the rotating part of the machine in which the voltage is induced.
armature
The rotating member of the DC generator is the ------
armature
If a circuit contains a large amount of resistance ans a small amount of inductance, the resistance and impedance will ----
be nearly the same.
A ---- may perform a variety of jobs, such as just storing an electrical charge to produce a large current pulse, providing voltage for timing circuits, or making a power factor correction.
capacitor
Electrical systems that have series and parallel combinations of components in the same circuit are referred to as --- circuits or complex circuits.
combination
in the DC generator, the components used to remove the voltage from the armature are brushes in a ---
commutator
The term --- refers to the method of creating the magnetic field in the rotor.
conduction motor
The transfer of electrons from atom to atom is the actual transfer of energy along a --- path
conductive
---- have magnetic fields produced as current moves through them.
conductors
The basis for the operation of an electric motor is that the relation of magnetic properties holds true as we apply current to a ---- and produce a magnetic field then bring two magnetic fields into close proximity.
conductors
The --- of angle theta, is equal to the power factor.
cosine
The voltage induced in a inductor by the changing magnetic filed is knows as ---
counter EMF
A capacitor can charged to a DC value and then appears as a ---- to the applied voltage.
counter-voltage
Once we know that circuit impedance of all the combination RLC circuit components combined into one equivalent component, we can determine the circuit ---- when a known voltage is applied.
current
The ---- is the same volume at any point in a series circuit.
current
The voltage drop across a resistor will be in pahse with the ---
current
Using the ---- for the reference in a series circuit simplifies the analysis.
current
Since they induce EMF appears only during a change in the ----, the magnitude of the self induced EMF depends on the rate of change of the current and the amount of inductance.
current flow
As we add more capacitors in series, the total capacitance of the circuit --- , similar to what happens as we add resistors in parallel.
decreases
The circular mil area of a conductor is defined as ---- the of the conductor in mils squared.
diameter
A capacitor consists of two conducting surfaces, usually referred to as plates, separated by some type of insulating material, called the ----
dielectric
They type of --- used is an important factor in determining the amount of capacitance a capacitor will have.
dielectric
Voltage rating of a capacitor is the amount of voltage differential that the --- can withstand before puncturing or breaking down.
dielectric
in the very early years of electrical power, ---- current was the most widely used form of electricity.
direct
the battery is the primary source of ---- current.
direct
Because inductance and inductive reactance are ---- ,the same rules that apply for inductors in parallel are also used to determine inductive reactance in parallel.
directly proportional
When a voltage is induced into a conductor as it is passed through a magnetic field, the effect is called---induction.
electromagnetic
The term --- refers to the fact that is has an electrical charge that is stationary.
electrostatic
When an inductor and capacitor are connected in series, there is a frequency at which the inductive reactance and capacitive reactance will become ---
equal
When Ohm's law is used on the circuit values, the sum of the voltage drops developed across these components can --- the applied voltage.
exceed
In an inductive circuit, the current changes at an ---- rate when the source voltage changes.
exponential
The value of circuit capacitance opposition can be calculated using the capactitive reactance formula when the capacitance is in ---
farads
Frequency has an effect on capacitive reactance because the capacitor charges and discharges ----- at higher frequency.
faster
The greater the voltage applied, the greater the current flow and, therefore, the greater the created magnetic ---
flux
The total number of ---- lines and the inductance are directly related to the number of turns of wire.
flux
The term ---- may be familiar to many younger electricians. It was a term used in the movie back to the Future to refer the power production device on the vehicle that transported the main character back in time.
flux capacitor
The process of using both legs with part of the primary and secondary winding on each leg reduces the Transformer losses the result from ----
flux leakage
The effects of changing values in a parallel RLC circuit can depend on the...
frequency
The excitation power input of the electromagnetic exciter affects the peak to peak voltage but not the ----
frequency
The number of complete waveforms completed in one second is known as ....
frequency (Hz)
A ---- it's a device that converts mechanical energy to electrical energy.
generator
A low-pass filter blocks the --- frequency
higher
resistance and capacitive reactance are 90 degrees out of phase with each other, and these form a right triangle with the impedance, forming the---
hypotenuse
If a circuit contains a large amount of resistance and a small amount of inductance, the resistance and, therefore, the ---- will be nearly the same.
impedance
One of the differences between DC and AC is the equivalent resistance in DC must be called equivalent - - - in AC.
impedance
the vector sum of the opposition's found in some AC circuits is known as ----
impedance
The ---- is developed by using vector representative of the opposition forces developed in the coil as a reaction to the AC fluctuations.
impedance triangle
Adding inductors in series with a circuit that already contains inductors will --- the total inductive reactance of the circuit.
increase
When adding resistive elements to a circuit that already has a coil, the opposition to the current ----
increase
Connecting capacitors in parallel has the same effect as ---- the plate area of one capacitor.
increasing
The effects of ---- are typically involved when we have a conductor, a magnetic field, and motion.
induction
When a circuit is not at resonance, current flow is limited by the combination of --- and capacitive reactance.
inductive reactance
Two of the more common forms of DC to AC ---- use in a variable frequency drives are known as current source input(CSI) and pulse width modulation(PWM).
inversion
The tree basic types of windings, depending on the needs of the machine are----
lap, wave, and frogleg.
If a circuit is more capacitive than inductive, the current will --- the voltage
lead
A capacitor with that weak dielectric will permit an unacceptable amount of current flow. This is called a ----.
leaky capacitor
The electrostatic field in a capacitor has the ability to hold less charge when the volts per mil thickness are ---
less
The total opposition to current flow in the circuit containing parallel inductors is always ----the opposition caused by the lowest-value coil or inductor.
less than
The total resistance of a parallel circuit is always --- the smallest resistance of any one branch.
less than
The use of --- steel reduces the losses due to hysteresis.
low-hysteresis
Typically, low pass filters are designed to deliver most of the signal to the load at --- frequencies.
lower
Inductors store energy in a ----
magnetic field
The purpose of the field is to produce ----
magnetic flux
The small primary current within a transformer it with not secondary current is referred to as exciting current, or ---- current.
magnetizing
When a filter is at its half-power point, the ---- power is dissipated by the resistor when the voltage on the load resistor is equal to the supply voltage.
maximum
AC generators or alternators change energy ---- from the prime mover to electrical energy.
mechanical
In the production of electricity, theyl need for --- is usually accomplished by a mechanical driven system (prime mover)
motion
The --- can be represented by the symbol nF
nano farad
The electron has an electrical charge with a ---- polarity
negative
The synchronous speed of an AC motor's rotating magnetic field depends on the --- and the frequency of the waveform applied
number of poles
One revolution per second for a two-pole generator creates ----
one Hertz
The current in the phase angle through each component are dictated by the --- encountered in each branch
opposition
The total impedance is equal to the total --- to current flow and the circuit.
opposition
The ---- is a tool that provides visual representation of a waveform.
oscilloscope
--- circuits have more than one path for current to flow
parallel
AS resistors are added in --- , we are actually adding more paths for current to flow.
parallel
The total inductance formula for two inductors in parallel is formatted the same way as the one for two resistors in ---.
parallel
When inductors are connected in parallel, the total inductance can be found using a formula that is similar to the one used for finding total resistance in ---- circuit.
parallel
as it is the case in all AC circuits, the --- factor is a factor apply to the apparent power of the circuit.
power
The inductive ---- actually creates a condition that causes the current to lag behind the voltage by 90 electrical degrees.
reactance
Angle theta may be calculated using the --- voltage drop and capacitive voltage drop values.
resistive
In a perfect conductor, there is no ---- and the current lags the voltage by 90 degrees.
resistive component
Power can only be dissipated or consumed by a --- ; therefore, there is nothing to add up unless it involves resistance.
resistive component
The easiest value to calculate in a parallel RLC circuit is the current flow through the ----
resistors
The same rules apply for inductive reactance as for ---
resistors
At ---- all reactive confidence are canceled and only the resistance of the circuit remains.
resonance
if all inductors are the --- ,use the concept that the total inductance is inductance of one coil divided by the number of coils.
same value
the voltage in a coil induces into itself has caused by the characteristics of-----
self inductance
The property of an electrical component ( such as a coil of wire) to induce a voltage into itself as the current through the component changes is known as----
self-inductance
Capacitors in parallel are calculated similar to inductors and resistors in ---
series
Most of the circuits you will work with will be a combination of ---- and parallel circuits.
series
capacitors in parallel are calculated similar to inductors and resistors in ---
series
The two types of field windings are the ----
series field and the shunt field
A --- wave is the result of a spinning conductor within a magnetic field.
sine
The impedance of the circuit could be calculated using the product of the oppositions divided by the of the ---- of the sum of the squares of the opposition, two components at a time.
square root
A --- rotor is made up of conductors that are mounted in the rotor and are short circuited at each end.
squirrel cage
Three phase induction motors use --- windings on the rutor just as single phase motors use.
squirrel cage
All AC motors work because a rotating magnetic field can be produced on a stationary frame, or the ----, of the motor.
stator
The ---- field in a single-phase AC motor can be created by having tow sets of coils displaced in physical location around the rotor.
stator
The revolving field generator allows the magnetic field to spin and the coils of wire where the voltage is induced to remain firmly attached to the stationary part of the generator known as the -----
stator
An electrical transformer designed to have lower voltage at the secondary terminals than it had at the primary terminals is known as a ---- transformer.
step-down
an electrical Transformer designed to have a higher voltage at the secondary output then it has a the primary input is known as a ----Transformer
step-up
When inductors are connected in series in a circuit, the total inductance is the ---- sum fo the inductances of all the inductors.
sum
the total resistance in a series circuit is the ---- of the individual resistors
sum
The ---- speed of an AC motor is the speed of the rotating magnetic field around the stator core, measured in revolutions per minute (rpm).
synchronous
The formula for determining the exact speed that a generator must spin to create a desired frequency is the ---- formula.
synchronous speed
A ---- circuit exists when a circuit contains an inductor and capacitor in parallel.
tank
reducing a complex circuit to a single equivalent load in source for a voltage is the method called the --- equivalent circuit.
thevenin
The Watts, or ---- , are found on the horizontal line of the power triangle and can be calculated by current times voltage across the resistive components or by current squared times resistance
true power
The in phase-power component can be calculated by the formula P=ExI and is known as ----
true power (Watts)
When the volt amps and watts are known, the power factor(PF) can be determined using the formula: PF = ---- / apparent power (VA)
true power (watts)
The condition that exists when the setup of the generator results in the no-load voltage being greater than the full-load voltage is known as ----
under compounding
The ---- capacitor is commonly thought of as a the adjustable capacitor that is used to tune radio frequency circuits.
variable
Because of the difference phase angles involved, ---- analysis is the only sure way to analyze a combination circuit with series and parallel combinations of components in and the same circuit
vector
Inductive reactants is represented as a --- drawn at 90 degrees to the horizontal.
vector
the value for the total current flow in a parallel RLC circuit can we calculated using --- addition of the current flow through each branch of the circuit.
vector
The stored electrical charge of a circuit or circuit component is in the form of ---
voltage
To determine the impedance of each parallel component vector in a combination RLC circuit, you can use the assumed --- method.
voltage
Power for the reactive components in a circuit is in ----
VARs
----- are electronic controls used to control the speed of an AC motor
Variable frequency drives
When a circuit containing both reactance and inductance is connected to alternating current, the total current will lag the applied voltage between ---- degrees
0 and 90
English physicist Michael Faraday discovered the basic theory of electricl generation in ----
1831
assume a resistor has a value of 6 ohms, and it is connected to a 12-volt source. when the switch is closed the current rises to----
2 amps
The synchronous speed of a two-pole generator is --- rpm to maintain 60 Hz
3600
Power factor is usually corrected to ---
95%
the amount of voltage is directly proportional to the changing amount of---- in the conductor and inversely proportional to the change in the time that occurs
AC current
Because the commutator is physically connected to the armature loop, the segments have an ---- voltage on them.
AC voltage
The volts-amps reactive (VARS) is found by the circuit current times the voltage across the ------ components.
Inductive, Capacitive, Reactive, (All of the above)
A ---- is an excellent application for the AC waveform that is constantly moving as time progresses.
Transformer
----- armatures are used in machines designed for high voltage and low current
Wave-woundR
The total resistance in a series circuit is found by ---- the values of the resistors in the circuit.
adding
the component in the process of generation that has voltage induced into it, is known as the ---
armature
Power in the parallel circuit depends on the individual ----
branches
In a --- circuit, the current leads the voltage by 90 degrees.
capacitive
In the right-hand rule for motors, the ---- finger on the fight hand indicates electron flow direction in the armature conductor.
center
As capacitors are added in seines the total C ---
decreases
If the total inductance decreases, the total reactance ----
decreases
As resistors are added in parallel, we are actually adding more paths for current to flow and therefore are actually --- the total opposition of the circuit.
decreasing
The line-to-line voltage in a ---- pattern is the same as the phase voltage, unlike the arrangement in a wye system.
delta
In ----- circuits that contain both resistance and reactance, the branch currents are out of phase, and the voltage is the reference.
parallel
The voltage reference is the simplest choice for analyzing-----circuits
parallel
When resistance and capacitance are connected in----- the voltage across all the devices will be in phase and will have the same value
parallel
Two coils need to be ---- each other in order for their fields to create a coefficient of coupling and affect the mutual inductance
parallel to
By adding more ---- paths, we actually increase the number of current paths and reduce the total opposition of the circuit.
parallel.
The ----value is measured from zero to the highest value obtained in either the positive or negative direction.
peak
