Circuits
An inductor is rated by a unit named: a) Henry b) Lenz c) Ohm d) Farad
a) Henry
What happens when expanding lines of force have motion relative to a conductor? a) Voltage is induced b) current increases c) Power is increased d) Resistance is reduced
a) Voltage is induced
Total reactance in a series RLC circuit is the same as: a) XL = XC b) PT c) Z d) XL/XC
a) XL = XC
The unit of flux density is known as: a) a Telsa b) a Weber c) a Maxwell d) magnetomotive force
a) a Telsa
A generator requires: a) a fixed field and rotating armature b) a rotating field and fixed armature c) a fixed armature and field d) a rotating field and armature
a) a fixed field and rotating armature
A capacitor stores energy within a dielectric between the conducting plates in the form of: a) an electric field b) a magnetic field c) negative voltage d) positive voltage
a) an electric field
When a full band of frequencies is allowed to pass through a filter circuit to the output, the resonant circuit is called a: a) band pass filter b) high pass filter c) band stop filter d) low pass filter
a) band pass filter
The amount of electrons stored within a capacitor determines its: a) capacitance b) charge c) power d) current
a) capacitance
When a transformer secondary lead has been connected to a middle loop that is not an end connector, it is called a: a) center-tapped secondary b) multiple winding secondary c) multiple-tapped secondary d) single winding secondary
a) center-tapped secondary
A capacitor, like a secondary battery, can be made to: a) charge and discharge b) provide free electrons c) provide current d) reject voltage
a) charge and discharge
Inductance is proportional to the: a) coil area b) length of the coil c) way it is installed in the circuit d) capacitor used with it
a) coil area
A capacitor is constructed of two parallel: a) conductors b) semiconductors c) dielectrics d) inductors
a) conductors
Inductance is the ability of a coil to oppose: a) current change b) voltage c) voltage change d) current
a) current change
As a capacitor is being charged, current flowing into the capacitor will: a) decrease b) increase c) remain the same d) cannot tell
a) decrease
Indication of transformer primary and secondary voltage relationships is accomplished by: a) dot notation b) winding ratios c) color-coded wires d) black, rather than gray, casings
a) dot notation
What will electromagnetic induction cause? a) electrons to flow b) voltage to remain constant c) reluctance to decrease d) resistance to increase
a) electrons to flow
Which two values are plotted on a B-H curve graph? a) flux density and magnetizing force b) permeability and reluctance c) magnetizing force and permeability d) reluctance and flux density
a) flux density and magnetizing force
As a capacitor is being charged, the voltage across its terminals will: a) increase b) remain the same c) decrease d) cannot tell
a) increase
As the poles of a magnet are approached, flux density will: a) increase b) align the domains c) decrease d) remain the same
a) increase
If a relay control is low voltage and the contact circuit is high voltage, what will be the input to the coil when the controlling switch is closed? a) low voltage b) high voltage c) no voltage d) pulsed voltages
a) low voltage
The four factors determining inductance are the number of turns, coil length, coil area, and: a) permeability b) reluctance c) coefficient of coupling d) CEMF
a) permeability
Mutual inductance is achieved in a loaded transformer when: a) primary current is increased by an increase insecondary current b) secondary current increase causes a primary decrease c) secondary current decrease causes a primary increase d) primary current is decreased by an increase in secondary current
a) primary current is increased by an increase insecondary current
A Henry value divided by a circuit resistive value provides the: a) quality factor of the coil b) rise or decay time constant c) induced voltage amplitude d) counter EMF value
a) quality factor of the coil
If a charged capacitor is disconnected from a circuit, then it will: a) remain charged b) immediately discharge c) recharge d) leak the charge
a) remain charged
After the magnetizing force has been removed, the remaining magnetic flux is called: a) retentivity b) magnetic saturation c) coercivity d) hysteresis
a) retentivity
A value of "ten to the eighth power magnetic lines of force" is for the term: a) Coulomb b) Weber c) field d) flux
b) Weber
As current passes through a conductor: a) an electrostatic field opposes the current b) a magnetic field is developed around it c) the wire tries to point north d) the magnetic field aids the current
b) a magnetic field is developed around it
Capacitance is the ability to store: a) an impedance b) an electrical charge c) a magnetic field d) a resistance field
b) an electrical charge
When a parallel tank is used in series with an output load resistor the filter is: a) low pass b) band stop c) high pass d) band pass
b) band stop
A conductor's magnetic field is caused by: a) the apparent power generated b) current flowing through it c) the reactive power developed d) the voltage potential across it
b) current flowing through it
A magnetic circuit breaker will open to protect equipment only when: a) voltage is exceeded b) current is exceeded c) the equipment is operating properly d) an open is in the equipment
b) current is exceeded
Electromagnetic induction is the generation of: a) magnetism from electricity b) electricity from magnetism c) magnetism from magnetism d) electricity from electricity
b) electricity from magnetism
What is the transformer output to input relationship, when on a schematic, solid dots are placed at the top of both the primary and secondary transformer windings? a) 90 degrees out of phase b) in phase c) 180 degrees out of phase d) 45 degrees out of phase
b) in phase
When a coil collapses the induced circuit current will be: a) aid CEMF buildup b) in the same direction c) go to zero d) in the opposite direction
b) in the same direction
Adding an iron core inside a coil will: a) decrease total inductance b) increase total inductance c) reduce the quantity of the force field d) prevent flux linkage
b) increase total inductance
When the transformer secondary is not loaded: a) second current increases b) no secondary current flows c) secondary voltage increases d) no secondary voltage is present
b) no secondary current flows
A voltage is induced in a transformer secondary winding by the action of the: a) secondary counter EMF b) primary magnetic field c) secondary magnetic field d) primary turns ratio
b) primary magnetic field
If you wanted to decrease the inductance of a coil, you could increase the: a) number of turns b) spacing between turns c) the permeability of the core d) area of the coil
b) spacing between turns
A transformer would never be selected to: a) match impedances b) step-up or step-down power c) isolate stages d) step-up or step-down voltage
b) step-up or step-down power
What would be the power factor for an RLC circuit that acts inductively? a) -90 degrees lagging b) zero c) +90 degrees leading d) one
b) zero
At any resonant frequency, what voltage is measured across the two series reactive components? a) reactive voltage b) zero voltage c) applied voltage d) VL + VC voltage
b) zero voltage
When testing a power transformer with an ohmmeter, which winding should have the largest ohmic value? a) 5.0 V ac winding b) 120 V ac primary c) 600 V ac secondary d) 6.3 V ac CT winding
c) 600 V ac secondary
At resonance, the term bandwidth includes all frequencies that allow what percentage of maximum current to flow? a) 50 b) 62.3 c) 70.7 d) 95.3
c) 70.7
What is the phase angle in a purely inductive circuit? a) zero degrees b) 45 degrees c) 90 degrees d) 180 degrees
c) 90 degrees
In an RLC circuit, true power equals: a) VT x RT b) VS x I c) I^2R d) PR/PA
c) I^2R
A schematic representation of dashed lines between two vertical coils usually means that the transformer has: a) an air core b) an iron core c) a ferrite core d) a non-metallic core
c) a ferrite core
As a generator armature passes the 270 degree point, the induced voltage is: a) between maximum negative and zero b) at maximum positive c) at maximum negative d) between zero and maximum positive
c) at maximum negative
When an electromagnet reaches maximum strength, it is considered to be: a) at field strength b) inhibited c) at saturation d) in field condition
c) at saturation
Series resonance current is high because: a) source voltage is equal at each component b) zero volts is across the tank c) circuit impedance is resistive d) circulating current is high
c) circuit impedance is resistive
When relay action completes a circuit, the relay contacts are considered to be: a) normally open b) normally closed c) closed d) open
c) closed
All transformers are constructed to ensure: a) isolation b) self-inductance c) efficiency d) accuracy
c) efficiency
When a circuit consists of a capacitor and a resistor in series with a voltage source, and the voltage across the resistor becomes zero, then the capacitor is: a) charging b) fully discharged c) fully charged d) discharging
c) fully charged
A relay is used in an automotive starter circuit because: a) of driver safety b) high voltage is involved c) high current is involved d) of the high starter torque
c) high current is involved
The formula L × iDELTA/tDELTA provides what value in calculations concerning the inductor? a) inductor length b) current decay time c) induced voltage d) permeability
c) induced voltage
When XC = XL the circuit: a) applied voltage is zero b) draws maximum current c) is at resonance d) draws minimum current
c) is at resonance
What is one thing an auto-transformer cannot accomplish? a) transfer primary and secondary power b) step-down voltage c) isolate primary and secondary current d) step-up voltage
c) isolate primary and secondary current
In an RLC circuit, inductor current: a) leads VL b) is in phase with VR c) lags VL d) is in phase with VC
c) lags VL
The time required for one Weber of flux to cut a conductor and produce one volt is: a) one revolution b) four revolutions c) one second d) one millisecond
c) one second
The tank flywheel effect in a resonant, parallel RLC circuit is called: a) cut-off frequency b) selectivity c) oscillation d) parallel motion
c) oscillation
A series RL filter circuit with an output across the inductor will result in what type of filtering? a) passing of the lower frequencies b) blocking of the higher frequencies c) passing of the higher frequencies d) blocking of a certain range of frequencies
c) passing of the higher frequencies
In a coil, what is the ratio of energy stored vs energy dissipated called? a) counter EMF b) reactance c) quality d) power
c) quality
What principle is involved, when a coil induces a voltage within itself? a) coupling b) mutual inductance c) self-inductance d) impedance matching
c) self-inductance
When current in an inductor starts to change, it cannot react instantly due to: a) eddy current generation b) applied EMF of the circuit c) the CEMF of the coil d) fixed coil resistance
c) the CEMF of the coil
What component may a tuned transformer replace in a resonant circuit? a) the bandpass b) the flywheel c) the inductor d) the capacitor
c) the inductor
Fixed transformers have: a) a multiple-tapped secondary b) multiple windings c) turn ratios that cannot be changed d) a center-tapped secondary
c) turn ratios that cannot be changed
What effect will a parallel tank have upon final filter current? a) Bandpass frequencies will change b) Impedance will block output c) very little d) Frequency cut off will change
c) very little
In a parallel RLC circuit, which value may always be used as a vector reference? a) resistance b) reactance c) voltage d) current
c) voltage
If the charging current of a capacitor is increased, then what will happen to the current flow through its dielectric? a) decrease b) increase slowly c) increase immediately d) No current flows through a dielectric
d) No current flows through a dielectric
What will happen if the inductor's magnetic field collapses? a) Current will double b) CEMF will be high c) A new field will expand d) Voltage will be induced
d) Voltage will be induced
A change of one ampere per second in an inductor that induces a voltage of one volt is considered as which unit value? a) an Ohm b) a Lenz c) a Farad d) a Henry
d) a Henry
Capacitor construction separates metallic plates by using: a) battery acid b) a conductor c) an inductor d) a dielectric
d) a dielectric
A coil can consume electrical energy and store it in the form of: a) an electrical field b) a force field c) an electrostatic field d) a magnetic field
d) a magnetic field
Since current is the same throughout a series RLC circuit it may always be used as: a) a leading vector b) an angle c) a lagging vector d) a reference
d) a reference
When the transformer secondary is not loaded, the primary will: a) become a secondary CEMF buffer b) act as a dc block c) collapse d) act as a simple inductor
d) act as a simple inductor
Series RLC impedance or voltage totals must always be calculated by: a) subtracting the values b) graphing the angles c) multiplying the values d) adding values vectoriall
d) adding values vectoriall
When a series-resonant tank is used in series with an output load resistor, the filter: a) blocks the resonant frequencies b) passes high frequencies c) rejects high frequencies d) allows resonant frequencies to pass
d) allows resonant frequencies to pass
What is the name of the part inside a relay that is moved by the action of the electromagnet? a) conductor b) contacts c) solenoid d) armature
d) armature
Voltage lags current in an RLC circuit that acts: a) resonantly b) inductively c) resistively d) capacitively
d) capacitively
The magnetic field strength of an electromagnet will be decreased if one increases: a) core permeability b) coil wire diameter c) coil turns d) coil current
d) coil current
Coil magnetizing force may be decreased by increasing: a) coil current b) coil turns c) field intensity d) coil length
d) coil length
If a capacitor is discharging through a load, then the voltage across its terminals will: a) prevent current flow b) increase c) remain the same d) decrease
d) decrease
In a transformer, the primary and secondary coils are magnetically linked, but they are: a) current connected b) mechanically connected c) always in phase d) electrically isolated
d) electrically isolated
When measured, the voltage drop across an open series-connected inductor is: a) minus what is dropped across the meter b) varies with other components c) very low d) equal to VS
d) equal to VS
Maximum power will be transferred from the source, when the load impedance is: a) a multiple of the source b) more than the source c) less than the source d) equal to the source
d) equal to the source
When a magnet enters a coil and a voltage is induced, the process is known as: a) self inductance b) an alternation c) counter EMF d) flux linkage
d) flux linkage
The time difference, or lag, between flux density and magnetizing force is known as: a) eddy current b) coercivity c) magnetic saturation d) hysteresis
d) hysteresis
In an inductive circuit, reactance will: a) depend upon the value of XC b) decrease with frequency c) be independent from frequency d) increase with frequency
d) increase with frequency
Opposition to current flow without the dissipation of energy is called: a) impedance b) resistance c) counter EMF d) inductive reactance
d) inductive reactance
A magnetic field consists of: a) lines of reluctance b) polar fields c) magnetomotive force d) lines of force
d) lines of force
What produces secondary voltage in a transformer? a) the secondary counter EMF b) the winding ratio c) secondary winding direction d) magnetic flux cutting secondary windings
d) magnetic flux cutting secondary windings
Voltage drops around a series RLC circuit, when added together will equal a total: a) less than the source voltage value. b) three times the source voltage value c) the same as the source voltage value d) more than the source voltage value
d) more than the source voltage value
What does an armature do in a magnetic circuit? a) provide a virtual path to ground b) conduct current c) remain stationary d) move
d) move
When transformer secondary leads have been connected to several different loops that are not end connectors, the secondary is considered: a) single-wound b) multiple-wound c) center-tapped d) multiple-tapped
d) multiple-tapped
What term is used to describe the action of magnetic flux from one circuit that cuts across the conductors of another circuit? a) self inductance b) magnetism c) rectification d) mutual inductance
d) mutual inductance
The polarity of induced voltage while a field is collapsing is: a) identical to the force creating the field b) present only if force is stationary c) independent of the force creating it d) opposite to the force creating it
d) opposite to the force creating it
What is one characteristic of an inductor? a) develops high reactance to dc b) blocks dc c) develops high resistance to dc d) passes dc
d) passes dc
During a current change, the ability of a conductor to produce counter EMF within itself is called: a) impedance b) a Henry c) back EMF d) self-induction
d) self-induction
The formula to determine total inductance when inductors are connected in parallel is similar to: a) series resistors b) series inductors c) parallel capacitors d) series capacitors
d) series capacitors
What type of device consists of a coil with a moveable iron core? a) relay b) reed switch c) armature d) solenoid
d) solenoid