32 Chapter 3 Science of Electricity and Electronics W e are fortunate to live in an age with advanced technology capable of studying the electron. New discoveries, developments, and applications in electronics occur almost daily. Th ese present unlimited opportunities for the creative scientist, as well as for the skilled technician. OBJECTIVES After studying this chapter, you will be able to: ■ Identify the relationship between elements and compounds. ■ Construct a model of an atom. ■ Discuss the concepts of atomic weight and atomic number. ■ State the law of charges and give several examples. ■ Defi ne electric current, voltage, and resistance. ■ Describe the two theories of current direction. ■ Distinguish between conductors, insulators, and semiconductors. ■ State and explain Ohm’s law. KEY TERMS alternating current (AC) ampere (A) atom atomic number atomic weight compound conduction conductor conventional current fl ow theory coulomb current direct current (DC) electromotive force (EMF) electron fl ow theory electrons electrostatic fi eld electrostatic precipitator element induction insulators ionized load matter molecule negative ion neutrons nucleus ohms Ohm’s law parallel circuit positive ion protons resistance semiconductor series circuit static electricity volt (V) voltage