4B module 1 test

Most commercial alternating-current power is produced by a generator driven by _____.

Any of these

The voltage produced by an ac generator is dependent upon the _____.

All of these

In circuits with _____ loads, the voltage waveform finishes after the current waveform so the voltage "lags" the current.

Capacitive

A waveform is a mathematical representation on a graph that can be used to visualize the level and direction of _____ in a circuit.

Current or voltage

A simple ac generator can be visualized as a loop of wire rotating within the magnetic lines of force between similar poles of a magnet.

False

The peak value of a waveform is the maximum value the current or voltage waveform reaches during each full cycle of the rotation of the generator's rotor.

False

In circuits with _____ loads, the voltage waveform finishes its cycle before the current waveform, so the voltage waveform "leads" the current waveform.

Inductive

A nonsinusoidal (or nonsymmetrical) waveform is produced when multiple alternating-current waveforms of different frequencies are introduced on a circuit, typically by _____.

Nonlinear loads

When the term "_____" is used in relation to waveforms, it indicates the degree relationship between two waveforms, such as voltage-to-current or voltage-to-voltage.

Phase

A _____ load has its voltage waveform finishing its cycle at the same time (without lead or lag) as the current waveform.

Resistive

A "lagging" waveform is when the voltage lags behind the current and a "leading" waveform means the voltage leads the current.

True

A pure direct-current waveform displays the polarity and magnitude of the current or voltage as a flat waveform.

True

A three-phase generator has each of its three windings evenly spaced around the rotor and the windings are 120° out-of-phase from each other.

True

Current flow in an alternating-current circuit moves in both directions due to the changing polarity of the voltage, whereas direct current flows only in one direction.

True

Depending on the instant selected, the instantaneous value can range anywhere from a zero, to a positive peak, or to a negative peak.

True

Effective current value is also known as the "Root-Mean-Square" (RMS) value.

True

For current to flow through a circuit, the power source must apply enough electromotive force (voltage) to cause electrons to flow.

True

Frequency is expressed as cycles per second, or Hertz (Hz).

True

The effective value of ac voltage or ac current is the equivalent value of dc voltage or dc current that would produce the same amount of heat in a resistor

True

The waveform for alternating-current circuits is symmetrical with positive above and negative below the zero-reference level.

True

Waveforms that are "in-phase" with each other means that at every instant, the current is exactly in step with the applied voltage, and both the current and voltage waveforms reach their zero and peak values at the same instant in time.

True

When a magnetic field moves through a coil of wire, the lines of force of the magnetic field cause electrons in the wire to flow in a specific direction. When the magnetic field moves in the opposite direction, electrons in the wire flow in the opposite direction.

True

When describing the relationship between voltage and current waveforms, the reference waveform (the one used to compare against) is the _____.

Voltage