Chapter 1 Electrical Fundamentals Review 17 Copyright Goodheart-Willcox Co., Inc. Copyright Goodheart-Willcox Co., Inc. Summary • The basic units of electricity are current (I), voltage (E), and resistance (R). • Work is the process by which an electrical circuit transforms energy from one type to another. Power (P) is the rate at which this work is done. • Series circuits have only one pathway for current. Parallel circuits have several pathways for current. • Complex circuits can be broken down into equivalent circuits by applying the concepts of both series and parallel circuits. • Ohm’s law shows the relationship between current, voltage, and resistance, and can be used to fi nd missing values in a circuit. • Alternating current (ac) is constantly changing direction, while direct current (dc) always fl ows in one direction. • An alternator, or ac generator, is composed of an armature, poles, slip rings, and brushes. • Inductive devices create electromagnetic fi eld that decrease the response speed of a circuit. • Capacitance (C) is the ability of a material to store an electric charge. • Impedance (Z) is the total opposition to the fl ow of alternating current (ac). • Power factor is a ratio of true power to apparent power. • There are fi ve basic voltage systems derived from utility-supplied distribution. • A nominal voltage indicates a desired level of supply voltage for a system, while a rated voltage is the preferred voltage for equipment. Know and Understand Answer the following questions using the informa- tion provided in this chapter. 1. The rate of fl ow of electricity is known as _____. A. current B. voltage C. resistance D. All of the above. For Questions 2–5, match the units to the electrical characteristic. 2. Units of current. 3. Units of voltage. 4. Units of resistance. 5. Units of power. 6. True or False? A circuit that has three separate pathways for current is considered a series circuit. 7. True or False? In a parallel circuit, the voltage is equal across all branches of the circuit. 8. True or False? Alternating current (ac) is easier to produce than direct current (dc). 9. In an alternator, the _____ transfer current to the external circuit. A. armatures B. poles C. slip rings D. brushes 10. A basic type of inductive device is a _____. A. lamp B. core C. coil D. All of the above. 11. True or False? Impedance is the enhancement of the fl ow of alternating current. A. amperes B. ohms C. volts D. watts