DELMARS STANDARD TEXTBOOK

Instructor’s Guide to Accompany

DELMAR’S STANDARD TEXTBOOK

OF ELECTRICITY

Sixth Edition by Stephen L. Herman and Kerry A. Reinhackel

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SECTION 1

Safety, Basic Electricity, and Ohm’s Law

OUTLINE

S-1 General Safety Rules S-2 Effects of Electric Current on the Body S-3 On the Job S-4 Protective Clothing S-5 Ladders and Scaffolds S-6 Fires S-7 Ground-Fault Circuit Interrupters S-8 Arc-Fault Circuit Interrupters S-9 Grounding Key terms Artificial respiration Cardiopulmonary resuscitation Confined spaces De-energized circuit Disconnect Energized circuit Fibrillation Fire-retardant clothing Horseplay Idiot proofing Lockout and tagout Material Safety Data Sheets (MSDS) Meter Milliamperes (mA) Occupational Safety and Health Administration (OSHA) Scaffolds Safety Overview Anticipatory Set Go over the eleven objectives of this unit and ask students what they already know about any of the objectives mentioned. Promote classroom discussion on the subject of safety. Be careful to correct any mistakes.

UNIT 1

Atomic Structure

OUTLINE

1-1 Early History of Electricity 1-2 Atoms 1-3 The Law of Charges 1-4 Structure of the Atom 1-5 Electron Orbits 1-6 Valence Electrons 1-7 The Bump Theory 1-8 Power Sources 1-9 Insulators 1-10 Semiconductors 1-11 Molecules 1-12 Methods of Producing Electricity 1-13 Electrical Effects 69774_sec01_ptg01.indd 108/09/14 4:53 PM 2 / 4

2 Anticipatory Set To prepare students for this unit, begin by stating the four objectives of the unit. Then, ask students what they ­already know about any of the four objectives. You may need to do a little prompting, such as asking what they remember or know about atoms, positive/negative charges, things that conduct electricity, or things that do not conduct electricity. Ask if anyone knows why you don’t use electrical tools in the rain, or why you do use rubber boots to protect you from shock when working on a damp floor.1-1 Early History of Electricity Instruct students to be prepared to define key terms in their notes as you proceed through the unit. Briefly discuss the two basic types of current. Follow up with a brief explanation of repulsion and attraction. Have some examples from list A or B (p. 32 of text) to show these principles in action. Distinguish between negative and positive charges as they relate to attraction and repulsion. Ask students if they know any other examples. Check for understanding by asking one or more students to explain the attraction/repulsion process.1-2 Atoms Define an atom. Discuss the three principle parts of the atom, and discuss the role of each part as it relates to the make-up of the 90 natural elements and 23 artificial elements. Check for understanding before moving on.1-3 The Law of Charges Begin discussion of the law of charges with a reminder of the principles of attraction/repulsion. This will help the students to immediately begin using previous learning as building blocks on which to attach new information.This is a good time to explain that everything in this text will build on principles learned, unit by unit. Discuss charges that attract and charges that repel. Using the PowerPoint ® presentation, follow the outward-going and inward-going charges. ­Explain the two theories about why protons having the same charge do not break apart in the nucleus. Check for understanding. Have students draw the proton-electron relationship and the proton-proton relationship in their notes.1-4 Structure of the Atom Ask students for to explain the similarities between how the planets orbit the sun in the solar system and the man- ner which electrons orbit the center of the atom. Point out that both the planets and electrons exist in exact specific orbits determined by their size (mass) and speed.1-5 Electron Orbits The section on electron orbits may call for a review of some basic mathematics.When discussing electron orbits, be sure that students understand how to determine the maximum number of electrons that can be in any given orbit. To check for understanding of the 2(N) 2 formula, write some ar-

bitrary possibilities on the board or overhead: 2(5)

2

, 2(3)

2

, 2(8)

2 , and so on. Have students tell you how many electrons are in the orbit, and the number of the orbit, or shell: 50/5th orbit, 18/3rd orbit, 128/8th orbit, and so on.Stop here, and review the definitions of all key terms covered in the first five sections: direct current, alternating current, repulsion, attraction, atom, matter, element, electron, neutron, proton, quarks, nucleus, atomic number,

KEY TERMS

Alternating current (AC) Atom Atomic number Attraction Bidirectional Conductor Direct current (DC) Electron Electron orbit Element Insulators Matter Molecules Negative Neutron Nucleus Positive Proton Repulsion Semiconductors Unidirectional Valence electrons 69774_sec01_ptg01.indd 208/09/14 4:53 PM 3 / 4

3 opposite and like charges, and gluon. Have students explain these various terms. Review how they are related to each other.1-6 Valence Electrons Explain valence electrons and explain that the inner shells will have more electrons than the valence shell, as explained with 2(N) 2 . Good examples of this are PowerPoint slides corresponding to Figures 1–15 and 1–16. Explain how atoms with fewer valence electrons make better update conductors and why atoms with a higher number of valence electrons resist conductivity.1-7 The Bump Theory Discuss electron flow using the cue ball example. Ask students to give other examples (shuffle board, croquet, etc.).Be sure that students understand the directional flow of the energy from the impacting electron and how that energy is split by this directional flow, lessening the energy flow in each direction.1-8 Power Sources Discuss the fact that all electrical sources develope a positive and negative pole, and that current will always flow from the more negative source to the more positive source.1-9 Insulators Review what the maximum number of valence electrons is (8) and how this results in the creation of insulators.Have students give examples of insulators used in various professions (boots, gloves, etc.) or in household appliances (electrical cords).1-10 Semiconductors Explain semiconductors and give examples of how they are used (in computers, for example).1-11 Molecules Define molecules, and have students distinguish between molecules and atoms. See if students can explain, using what they have learned about electrons and valence shells, how two atoms might form a compound.1-12 Methods of Producing Electricity Go over, one by one, each of the ways to produce electricity. Discuss the benefits of using one way over another, for a particular purpose. Point out terms the student should become familiar with, such as piezo, Seebeck, photons, pho- tovoltaic, photoemissive, photoconductive, solar cells, and cad cells. Take some time to discuss the production of electricity from light, as it is so widely used.1-13 Electrical Effects Discuss how electricity can create some of the various effects, heat, light, pressure, magnetism, and chemical reac- tions that it is created from. Give examples of the various uses of electricity, in these ways. For example, if you have access to a crystal radio or earphone, it would be extremely beneficial for the student to see this process in action.Perhaps you can copper plate something, or discuss the difference in buying gold plated jewelry versus solid gold jewelry. Perhaps a discussion of the way electrolysis is used would also be helpful. Having a variety of light bulbs, of different wattages, might be a good way for students to explain how light is produced, and the results in heat watts and light watts.Unit Round Up Review all terms from the unit, including those terms covered in Sections 1-6 through 1-11: valence electrons, con- ductor, electron flow, insulators, semiconductors, and molecules. Review basic principles covered in the unit, and check for understanding by having students explain to you how these principles work. It is also a good idea for the instructor to review the test from the Instructor’s Guide to assure that all necessary material was covered well enough for students to answer all test questions.

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