Chapter 7 Alternating Current, Power Distribution, and Voltage Systems

The effective voltage of an alternating current circuit is ____________________ times its peak voltage.

0.707

What is the common electrical service to a residence?

240-volts single phase-60 Hz

Alternating current reaches a peak at ____________________ electrical degrees, also known as the peak voltage.

90

________ is caused in AC circuits by using capacitors. When a capacitor is put in an AC circuit, it resists the change in voltage, causing the amperage to lead the voltage.

Capacitive reactance

The frequency is known as ohms but many times, it is referred to as cycles.

False Response Feedback: Rationale: The frequency is known as hertz (Hz), but many times it is referred to as cycles.

One cycle occurs when the rotor, or conductor, cuts the magnetic field of a north pole and south pole.

True

Alternating current is ________________.

all of these

There are two types of electric current: direct current and ____________________ current.

alternating

Alternating current is produced by a(n) ____________________.

alternator

240-Volt-Three-Phase-60-Hertz ____________________ system is used in structures that require a large supply to motors and other three-phase equipment.

delta

In the United States, the common frequency is 50 Hz.

false

The frequency of alternating current is the number of complete cycles that occur in a minute.

false The frequency of alternating current is the number of complete cycles that occur in a second.

What is the sum of the resistance and reactance in an alternating current?

impedance

The ______________ of an AC circuit is the number of currents alternating at different time intervals in the circuit.

phase

The ratio between the true power and the apparent power is called the ________.

power factor

________ is the resistance that alternating current encounters when it changes flow.

reactance

The alternator is made up of a winding, or set of windings, called the ________ and a rotating magnet called the ________.

stator; rotor

Single-phase current has only a single current, while three-phase current has _______ separate currents.

three

Because alternating current starts at zero, reaches a peak, and then returns to zero, there is always a variation in voltage and an effective value has to be determined.

true

Direct current is an electron flow in only one direction.

true