Chapter 5

When describing the relationship between voltage and current, the reference waveform is always ____.

voltage

In purely inductive circuit, the CMF waveform is ____ out of phase with the applied voltage waveform.

180

The waveform of the CEMF is _______ out-of-phase with the applied voltage.

180

The induced voltage in a conductor carrying alternating current opposes the change in current flowing through the conductor. The induced voltage that opposes the current flow is ____."

CEMF, counter-elecromotive force, back-EMF

A half-wave rectifier can be used to convert ac voltage into dc voltage to continually charge a capacitor.

False

Even when power is removed from the circuit, capacitors can store large amounts of energy for a long period of time. They can discharge and arc if inadvertently shorted or grounded out.

True

The magnitude of self-induced voltage within a winding is directly proportional to the current flow, the winding, and the frequency at which magnetic fields cut through the winding.

True

The movement of electrons themselves does not produce any useful work. It's the effect that the moving electrons have on the loads they flow through that are important.

True

When alternating current increases, the polarity of the CEMF within the conductor tries to prevent the current from increasing.

True

Self-induced voltage opposes the change in current flowing in the conductor. This is called "inductive reactance" and is abbreviated as

X L

The abbreviation for impedance is ____

Z

The opposition offered to the flow of alertnating current by a capacitor is called "capacitive resistince," which is expressed in ohms and abbreviated _____.

Z

Self-induced voltage is 180 degrees out of phase with the _____. When the applied voltage is at the maximum in one direction, the induced voltage is at its maximum in the opposite direction.

applied voltage

For ac circuits, the ac _____ of a conductor must be taken into consideration.

eddy currents induced voltage impedance

The total opposition to current flow in ac circuits is called ______ and is measured in ohms.

impedance

In a resistive ac circuit, the current and voltage are _____. This means that they both reach their zero and peak value at the same time.

in-phase

The movement of electrons caused by an external magnetic field is called "_____ current," and the associated potential that is established is called "____ voltage."

induced

A nonsinusial waveform is created when ______ loads distort voltage and current sine wave

nonlinear

In dc circuits, the only property that affects voltage and current flow is _____.

resistance

As the alternating current through a conductor increases, an expanding and collapsing electromagentic field through the conductor includes a voltage within the conductor. This is know as "____ voltage."

self-induced

The expanding and collapsing magnetic field within the conductor induces a voltage in the conductors that repels the following electrons toward the surface of the conductor. This is called ______.

skin effect

The effective value is equal to the peak value ____

times .707

The peak value is equal to the effective value ______.

times 1.14