NCATT Chapt 3 Concepts of AC
Amplitude – answer AC is current that constantly changes in _____ and that reverses
direction at regular intervals
Transformer - answer Unlike direct voltages, alternating voltages can be stepped up or
down in amplitude by a device called _____
Magnetic force - answer If a compass is placed in the vicinity of a current-carrying
conductor, the compass needle will align itself at right angles to the conductor,
indicating the presence of a _____
Left hand - answerIf you hold a conductor in your _____ with the thumb extended in the
direction of the electron flow (current, negative to positive), your fingers will point in the
direction of the magnetic lines of force.
Hysteresis loss - answerWhen AC changes direction , the alignment of the atoms in the
coil also changes, causing a loss of power known as _____
Frequency - answerIf the loop in a generator completes on full cycle per second, the
_____ is 1 Hz
Alternations - answerIn a sine wave, the positive and negative _____ are identical in
shape and size but opposite in polarity.
The instantaneous value - answer_____ of an alternating voltage or current is the value
of voltage or current at one particular instant
0.636 - answerThe average value of alternating current is _____ times the peak value
In phase - answerWhen two sine waves are exactly in step with one another, they are
said to be _____
Inductance - answer_____ is the characteristic of an electrical circuit that opposes the
starting, stopping or a change in value of the current.
Core - answerAn inductor is made by forming a coil of wire around a _____, which is
usually soft iron or air.
Five - answerMaximum currents flows in the inductor after _____, L/R time constants
are completed
Amplitude – answer AC is current that constantly changes in _____ and that reverses
direction at regular intervals
Transformer - answer Unlike direct voltages, alternating voltages can be stepped up or
down in amplitude by a device called _____
Magnetic force - answer If a compass is placed in the vicinity of a current-carrying
conductor, the compass needle will align itself at right angles to the conductor,
indicating the presence of a _____
Left hand - answerIf you hold a conductor in your _____ with the thumb extended in the
direction of the electron flow (current, negative to positive), your fingers will point in the
direction of the magnetic lines of force.
Hysteresis loss - answerWhen AC changes direction , the alignment of the atoms in the
coil also changes, causing a loss of power known as _____
Frequency - answerIf the loop in a generator completes on full cycle per second, the
_____ is 1 Hz
Alternations - answerIn a sine wave, the positive and negative _____ are identical in
shape and size but opposite in polarity.
The instantaneous value - answer_____ of an alternating voltage or current is the value
of voltage or current at one particular instant
0.636 - answerThe average value of alternating current is _____ times the peak value
In phase - answerWhen two sine waves are exactly in step with one another, they are
said to be _____
Inductance - answer_____ is the characteristic of an electrical circuit that opposes the
starting, stopping or a change in value of the current.
Core - answerAn inductor is made by forming a coil of wire around a _____, which is
usually soft iron or air.
Five - answerMaximum currents flows in the inductor after _____, L/R time constants
are completed
