Electrical Calculations. (Unit 3) Alternating Current.

A self-induced voltage waveform, also known as counter-electromotive force (CEMF), is _____ out-of-phase with the applied voltage waveform.

180°.

The amount of self-induced voltage created within a winding is directly proportional to _____.

Current flow. The number of wire loops (or turns). Frequency at which the expanding and collapsing electromagnetic fields cut through the wires of the winding.

For alternating current, the effective value can be determined by using which of the following formulas?

Effective Value = RMS Value. Effective Value = Peak Value x 0.707. Effective Value = Peak Value/1.414.

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.

Another use for a capacitor is starting single-phase motors. A "start" capacitor is connected to the rotor circuit to create the initial electromagnetic field for the rotor to begin moving.

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.

If a capacitor becomes overcharged, the electrons from the negative metal plate can be pulled through the insulation (dielectric) to the positive metal plate by an excessive electric field.

True.

The total power consumed in a parallel circuit equals the sum of the powers in each branch.

True.

True power is the total energy consumed and is expressed in _____.

True.

Voltage induced in a wire by its own expanding and collapsing electromagnetic field is known as "self-induced voltage."

True.

Power is the rate at which electrical energy is transferred by an electric circuit in a given amount of time at a steady rate and is measured in _____.

Watts.

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.

Capacitance is measured in units of _____.

farads.

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

inductive.

Eddy currents are small independent currents near the center of a wire that are a result of _____ from the expanding and collapsing electromagnetic field.

self-induction.

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

voltage.