Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Essentials of Electronics Second Edition Frank D. Petruzella Glencoe/McGraw-Hill CHAPTER 3 CONDUCTORS, SEMICONDUCTORS AND INSULATORS Most materials belong to one of three broad groups: conductors, insulators, and semiconductors. The borderlines are not clear, though, and many substances cannot easily be put into one group or the other. CHAPTER 3 CONDUCTORS, SEMICONDUCTORS AND INSULATORS In this chapter you will learn about the atomic structure of each group. OBJECTIVES 1.Describe the structure of an atom. 2.Recognize, at the atomic level, the characteristics of conductors, semiconductors, and insulators. 3.Explain the ionization process. 4.Recognize common conductor, semiconductor, and insulating materials. 5.Define electricity. Key Definitions • Electron Theory of Matter: – All matter, solid, liquid, gas, is comprised of molecules, which in turn are comprised of atoms, which are again comprised of protons, neutrons and electrons. • Define Molecule: – The smallest part of matter which can exist by itself, still retains properties of original substance. Structure of an atom Shell or energy level: how electrons are arranged around the nucleus, An atom is the smallest particle of matter, contains E,P,N’s. Proton Neutron Electron Bohr model of the aluminum atom 13 P 14 N Protons = Electrons 13=13 Net charge is neutral or zero Placement of electrons in a copper atom Complete with 2 Complete with 8 +29 Complete with 16 Incomplete with 1 Electricity-the flow of free electrons Valance electron Positive source Negative source Bound electron Free electron Atomic structure of conductors, insulators, and semiconductors Conductor - 1 to 3 valence electrons Insulator - full valence shell Semiconductor - 4 valence electrons Common Conductors and Insulators Conductors Insulators Continuity Tester • What is Continuity? – Determines if a circuit is complete. • How is measured? – Low resistance = continuity – High resistance = no continuity. • How might you be able to build a basic continuity tester? – Lamp, battery, test leads… Continuity Tester Lab Continuity test (closed circuit) Lamp “on” Copper wire conductor Continuity test (open circuit) Lamp “off” Insulator Continuity Tester Light “on” indicates continuous path Tester internal circuit Electronic Devices What is Solid state? Uses electron tubes or semiconductors. What does it mean to be electronic? Uses semiconductors. Electron tube Integrated circuit Transistor