CH. 16 Inductive AC Circuits

Unity power factor is a power factor equal to ____________________.

1

When a ratio of ___ to 1 exists between the inductive reactance and the resistance, the circuit is usually considered a pure inductive or pure resistive circuit, depending on which of the two is larger.

10

In an inductive AC circuit, CEMF is ___° out of phase with the source voltage.

180

Inductive current leads CEMF by ___°.

90

Inductive reactance is affected by the size of the inductor and ___.

AC Frequency

The ability of a circuit containing both resistance and reactance to conduct current is known as ___.

Admittance

The greater the ratio of inductive voltage drop to resistive voltage drop, the greater the ___.

Angle Theta

In a series resistive AC circuit, true power is equal to ____________________.

Apparent Power

Inductance opposes any change in ___.

Current

____________________ is used to calculate most parameters in a parallel inductive-resistive circuit.

Current

Power ____________________ is the ratio of true power to apparent power.

Factor

Admittance is the phase difference between the source voltage and resistive voltage.

False

As frequency increases in a series inductive-resistive AC circuit, both impedance and current increase as well.

False

Current in an inductive AC circuit can be calculated without knowing source voltage.

False

Impedance aids the flow of alternating current.

False

Impedance is measured in joules.

False

In a parallel inductive-resistive AC circuit, the algebraic sum of the two currents is equal to the source current.

False

Inductors have no resistance.

False

Quality factor is measured in volt-amperes reactive.

False

The standard power source line frequency in Canada is 120 Hz.

False

The value of impedance is always less than that of reactance or resistance.

False

True power is measured in volt-amperes and apparent power is measured in watts.

False

A ___ change causes a change in inductive reactance.

Frequency

Under normal conditions, ____________________ does not change unless it is from a variable inductor.

Inductance

Impedance in an AC circuit can be found in the form of capacitive reactance or ____________________ reactance.

Inductive

____________________ changes directly in proportion with changes in either frequency or inductance.

Inductive Reactance

A voltage ____________________ is a vector diagram used to show the magnitude and phase of voltage in a series inductive-resistive AC circuit.

Phasor

The greater the frequency in a parallel inductive-resistive circuit, the greater the ____________________.

Power Factor

A(n) ___ must be used to measure reactive power and true power in an AC circuit.

Power Quality Meter

____________________ factor is the ratio of the inductive reactance to the resistance of an inductor.

Quality

Inductive ____________________ is the opposition of an inductor to alternating current.

Reactance

In an inductive-resistive AC circuit, almost all of the power is ___ power.

Reactive

____________________ is power supplied to a reactive load.

Reactive Power

The unit of admittance is the ___.

Siemen

___ is the ability of a reactive circuit to conduct current and is measured in siemens.

Susceptance

___ is the reciprocal of the reactive component of impedance.

Susceptance

A pure inductive circuit is an AC circuit with no resistance.

True

Although there is little true power in a pure reactive circuit, there is still current in the circuit.

True

Apparent power represents a load that has both true power and reactive power.

True

Counter electromotive force (CEMF) is created by a change in current, which is caused by a constantly changing magnetic field that cuts the inductor.

True

Current can be calculated in inductive AC circuits by modifying Ohm's law to substitute inductive reactance (XL) for resistance (R).

True

Frequency does not affect resistance in a parallel inductive-resistive AC circuit.

True

In a live circuit, it is not possible to separately measure inductive voltage and inductive resistance because the inductor is the resistive element.

True

In an inductive AC circuit, counter-electromotive force is 180° out of phase with the source voltage.

True

In inductive-resistive AC circuits, voltage is the same across all components connected in parallel.

True

Inductance can be held constant with the frequency varied, or frequency can be held constant with the inductance varied.

True

Kirchhoff's voltage law states that the algebraic sum of the voltage in a closed-loop circuit is equal to zero.

True

Only resistance can dissipate power in an electrical circuit.

True

Poor power factor exists when the power factor in a circuit is less than 90%.

True

The difference between true power and reactive power is that true power supplied to a resistive load is used to perform work or is dissipated as heat.

True

___ power in an inductive-resistive AC circuit is converted to heat in the inductor due to the resistance of the inductor.

True

Under normal conditions in power circuits, ___ power factor is the most desirable condition.

Unity

When analyzing an inductive-resistive circuit, ____________________ are used to calculate the effective voltage and phase difference between the inductive and resistive voltages.

Voltage Phasors

Reactive power is measured in ____________________.

Voltamperes Reactive

True power is measured in ___.

Watts