NCATT FROM WEBSITE EXAM
QUESTIONS WITH CORRECT
ANSWERS
Frequency - Answer-Number of cycles of AC completed in one second.
Frequency is expressed in hertz (Hz), 1 Hz = 1 cycle of AC/Second.
The frequency of most AC used in aircraft applications is 400 Hz.
Impedance (Z) - Answer-Electrical characteristic of a conductor. Impedance is the total
opposition to the flow of AC in an electrical circuit (resistance, capacitance, and
inductance).
Values are given in ohms.
Inductive Reactance (XL) - Answer-Opposition to current flow in a circuit.
The affect that inductance has on an AC circuit is termed inductive reactance.
Inductance causes current to lag voltage in phase (ELI). Values are given in ohms.
Phase Angle - Answer-Angle between two similarly varying quantities (sine-waves).
A phase angle is the difference in angle between two sinusoidally varying quantities
that have the same frequency.
Polyphase - Answer-Production of two or more phases of AC, or of two or more
alternating voltages of the same frequency.
The most common type of polyphase uses three phases.
Power Factor - Answer-Ratio of the actual power dissipated in an electrical system to
the input power of volts multiplied by amps.
The power factor is the ratio of power dissipated over input.
Rectifier - Answer-Electronic device that converts AC to DC.
o For example, a set of semiconductor diodes connected in a bridge circuit is a rectifier.
Root Mean Square (RMS) - Answer-Effective value of sine-wave alternating current.
The RMS value is .707 of the peak value.
Sine-Wave - Answer-Alternating current wave form produced by a rotary generator.
Sine-waves are values of voltage and current that start at zero and smoothly rise to a
peak value; the waves smoothly fall from a peak back to zero.
The waves then rise to a peak value in a negative direction and smoothly return to
zero.
, One AC cycle is produced by 360 degrees of rotation.
True Power - Answer-Power actually available in an AC circuit.
True power is the product of the circuit voltage and the current in phase with this
voltage.
Values are given in watts.
Wye Wound - Answer-Windings arranged in the shape of a Y.
For example, on a three-phase generator or transformer, one end of each of the three
windings is connected to form a common point.
Bridge Circuits - Answer-Contains four impedances that form a square.
Two diagonally opposite corners are connected to an input device.
The other two diagonally opposite corners are connected to an output device.
Complex Circuits - Answer-Contains a combination of series and parallel circuits.
Joules - Answer-International measure of energy expended in the kilogram, meter, and
second system of units.
Also known as a Newton-meter, a Joules is the amount of work done when a force of
one newton moves an object one meter along the direction of the force.
Kirchhoff's Current Law (KCL) - Answer-Kirchhoff's Current Law states that "the
algebraic sum of the current flowing away from any point in an electrical circuit is equal
to the sum of the current flowing to that point".
Kirchhoff's Resistance Law (KRL) - Answer-Kirchhoff's Resistance Law states that "the
total resistance in a series circuit is the sum of the individual resistances or loads in the
circuit".
Kirchhoff's Voltage Law (KVL) - Answer-Kirchhoff's Voltage Law states that "the
algebraic sum of all of the voltage drops in any closed circuit is equal to zero".
Parallel Circuits - Answer-Contains more than one path for current.
Circuit components are connected directly across each other.
Current is divided between each branch in the circuit.
Power - Answer-Product of applied voltage and current power in a DC circuit.
Product of applied voltage and the current in phase with the voltage in an AC circuit.
Resistors in Parallel Circuits - Answer-Causes a reduction of current in multiple circuits.
Resistors in Series Circuits - Answer-Causes a reduction of current in one circuit.
Series Circuits - Answer-Contains only one path for current, making current common
through all components.
QUESTIONS WITH CORRECT
ANSWERS
Frequency - Answer-Number of cycles of AC completed in one second.
Frequency is expressed in hertz (Hz), 1 Hz = 1 cycle of AC/Second.
The frequency of most AC used in aircraft applications is 400 Hz.
Impedance (Z) - Answer-Electrical characteristic of a conductor. Impedance is the total
opposition to the flow of AC in an electrical circuit (resistance, capacitance, and
inductance).
Values are given in ohms.
Inductive Reactance (XL) - Answer-Opposition to current flow in a circuit.
The affect that inductance has on an AC circuit is termed inductive reactance.
Inductance causes current to lag voltage in phase (ELI). Values are given in ohms.
Phase Angle - Answer-Angle between two similarly varying quantities (sine-waves).
A phase angle is the difference in angle between two sinusoidally varying quantities
that have the same frequency.
Polyphase - Answer-Production of two or more phases of AC, or of two or more
alternating voltages of the same frequency.
The most common type of polyphase uses three phases.
Power Factor - Answer-Ratio of the actual power dissipated in an electrical system to
the input power of volts multiplied by amps.
The power factor is the ratio of power dissipated over input.
Rectifier - Answer-Electronic device that converts AC to DC.
o For example, a set of semiconductor diodes connected in a bridge circuit is a rectifier.
Root Mean Square (RMS) - Answer-Effective value of sine-wave alternating current.
The RMS value is .707 of the peak value.
Sine-Wave - Answer-Alternating current wave form produced by a rotary generator.
Sine-waves are values of voltage and current that start at zero and smoothly rise to a
peak value; the waves smoothly fall from a peak back to zero.
The waves then rise to a peak value in a negative direction and smoothly return to
zero.
, One AC cycle is produced by 360 degrees of rotation.
True Power - Answer-Power actually available in an AC circuit.
True power is the product of the circuit voltage and the current in phase with this
voltage.
Values are given in watts.
Wye Wound - Answer-Windings arranged in the shape of a Y.
For example, on a three-phase generator or transformer, one end of each of the three
windings is connected to form a common point.
Bridge Circuits - Answer-Contains four impedances that form a square.
Two diagonally opposite corners are connected to an input device.
The other two diagonally opposite corners are connected to an output device.
Complex Circuits - Answer-Contains a combination of series and parallel circuits.
Joules - Answer-International measure of energy expended in the kilogram, meter, and
second system of units.
Also known as a Newton-meter, a Joules is the amount of work done when a force of
one newton moves an object one meter along the direction of the force.
Kirchhoff's Current Law (KCL) - Answer-Kirchhoff's Current Law states that "the
algebraic sum of the current flowing away from any point in an electrical circuit is equal
to the sum of the current flowing to that point".
Kirchhoff's Resistance Law (KRL) - Answer-Kirchhoff's Resistance Law states that "the
total resistance in a series circuit is the sum of the individual resistances or loads in the
circuit".
Kirchhoff's Voltage Law (KVL) - Answer-Kirchhoff's Voltage Law states that "the
algebraic sum of all of the voltage drops in any closed circuit is equal to zero".
Parallel Circuits - Answer-Contains more than one path for current.
Circuit components are connected directly across each other.
Current is divided between each branch in the circuit.
Power - Answer-Product of applied voltage and current power in a DC circuit.
Product of applied voltage and the current in phase with the voltage in an AC circuit.
Resistors in Parallel Circuits - Answer-Causes a reduction of current in multiple circuits.
Resistors in Series Circuits - Answer-Causes a reduction of current in one circuit.
Series Circuits - Answer-Contains only one path for current, making current common
through all components.
