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Unit One: Quantities, Units, and Electrical Safety

ET115 DC Electronics. Unit One: Quantities, Units, and Electrical Safety. John Elberfeld JElberfeld@itt-tech.edu WWW.J-Elberfeld.com. DC Electronics. In this course you will concentrate on controlling direct current using resistors

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Unit One: Quantities, Units, and Electrical Safety

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  1. ET115 DC Electronics Unit One:Quantities, Units, andElectrical Safety John Elberfeld JElberfeld@itt-tech.edu WWW.J-Elberfeld.com

  2. DC Electronics • In this course you will concentrate on controlling direct current using resistors • You will be using Digital Multimeters, power supplies, and resistors in most of your labs

  3. Computer Simulations • You will also use a computer program called MultiSim to build and test models of circuits in your labs

  4. Course Objectives - I 1. Perform conversions and calculations on electrical units of measure using metric prefixes, scientific notation, and engineering notation. 2. Explain standard electrical safety procedures. 3. Explain the Bohr model for atomic structure and how it relates to electrical concepts such as insulators and conductors including solids, liquids, and gases.

  5. Course Objectives - II 4. Identify electronic schematic symbols related to DC circuits. 5. Describe how to use components and sources such as resistors, rheostats, potentiometers, switches, batteries, and power supplies. 6. Explain what resistance is and its importance in electrical circuits 7. Apply Ohm’s Law and Watt’s Law to basic DC circuits.

  6. Course Objectives - III 8. Analyze series, parallel, and series-parallel circuits. 9. Apply Kirchhoff’s voltage and current laws to analyze DC circuits. 10. Apply voltage and current division rules to DC circuits. 11. Calculate the effect of a load on a voltage-divider. 12. Applying Thevenin’s theorem to simplify network circuits. 13. Explain the maximum power transfer theorem.

  7. Course Objectives - IV 14. Analyze circuit operation with multiple voltage sources using the superposition theorem. 15. Describe principles of operation for magnetic devices. 16. Use proper prototype board wiring and test procedures for DC resistive circuit components including using the digital multimeter. 17. Simulate and test DC circuits using Multisim.

  8. Classes • Classroom: Theory Room #_____ • Class day and time: ______________ • Lab Room: Lab #_______ • Lab day and time: ________________ • Bring to every class: • Textbook • Calculator with Engineering Mode • Lab supplies • Paper, pencil, etc

  9. Schedule • Expect to be in lab and class - working the full time • 11 class meetings • Review quiz every week • Unit tests weeks 5 and 8 • Week 11 Lab and Theory FINAL • If you miss more than 21 calendar days in a row you may be dropped from the class according to the school/financial aid regulations

  10. Requirements/Expectations • Come to class on time – EVERY CLASS! • Turn in your assignments when due • Points may be subtracted on unexcused, late assignments • Participate in class • Email me BEFORE class if you must be absent • Plan on 3-5 hours of homework • every week – sometimes more!

  11. Use Common Sense • Come to class on time, prepared to work until the end of class • Be courteous, respectful, honest, and helpful to your classmates and the instructor • Avoid distracting other students during class (no cell phones, use laptops ONLY for class projects, eat quietly and clean up afterwards, no chatting, etc.)

  12. Evaluation • Lab Exercises.............................30% • Assignments...............................25% • Quizzes…………………..............10% • Unit Exams.................................10% • Theory Final............................... 15% • Lab Final.....................….............10%

  13. 10% Quizzes • There are NO surprise quizzes – you will have a quiz or exam every week • Quizzes will be similar to your homework, which is similar to your exams and the final

  14. 25% Homework • Homework is assigned each week • Homework is due the next week • Sometimes a quiz on the homework will be used as a grade instead of grading your homework papers • “Reasonable” teamwork and cooperation on homework is acceptable • Copying is NOT acceptable

  15. 10% Unit Exams • Unit tests will be given weeks 5 and 8 and can include questions on all material covered to that point • Schedule of exams subject to revision • ITT requires these exams,which are created by ITT

  16. 30% Lab Exercises • These have the BIGGEST effect on your grade • Labs will be done each week • Cooperation and teamwork in lab are encouraged – copying is forbidden • Labs must be completed before you leave

  17. 10% Lab Final • On Week 11, you will do a lab, and a write up, which will be graded • Grade is based on the help received to complete the lab, and accuracy of your work

  18. 15% Theory Final • The Final exam will be given Week 11 • The exam is created by ITT and is standard for the course • 45 multiple choice questions worth 2 points off for each one wrong

  19. Progress • You can check with me for your current grade in class • If you are in danger of failing, you will be officially notified as soon as possible • Because we have only 10 classes where you will learn new material, missing just one class can set you behind – class attendance is the most important thing you can do!

  20. Schedule Unit Topic Chpt Labs • Quantities, Units, Safety 1 2 (#6-11) • Voltage, Current, Resistance 2 3 + 16 • Ohm’s Law 3 5 • Energy and Power 3 6 • Series Circuits Exam I 4 7 • Parallel Circuits 5 9 • Series-Parallel Circuits 6 10 • Thevenin’s, Power Exam 2 6 19 • Superposition Theorem 6 11 • Magnetism & Magnetic Devices 7 Lab Final • Course Review and Final Exam

  21. Unit One Objectives - I • Use scientific and engineering notation to represent quantities. • Perform arithmetic calculations using powers of ten. • Express electrical quantities with metric prefixes. • Convert among engineering metric prefixes (pico, nano, micro, milli, kilo, • mega). • Express measured data with the proper number of significant figures. • Define accuracy, error, and precision. • Round numbers properly.

  22. Unit One Objectives - II • Recognize electrical hazards. • Describe causes of electrical shock. • Discuss the effect of current on the human body. • List safety precautions to be observed when working with electricity. • Describe how Ground Fault Circuit Interpreter (GFCI) works. • Use a digital multimeter (DMM) to measure a predetermined low voltage on a power supply.

  23. Reading Assignment • Read and study • Chapter 1: Quantities and Units Pages 1-16 • Utility Voltages – Appendix DPages 323-324

  24. Lab Assignment • Experiment 1, Tables 1-5, 1-6, 1-7, and Review Questions Page 10 • (Most of this will be done IN CLASS rather than in the lab) • Rip out pages 3-10, staple them together, put your NAME on the pages, and turn them in before you leave the lab

  25. Written Assignments • Do all the problems on the homework handout • Be prepared for a quiz on questions similar to those on the homework. • If there are any calculations, you must show ALL your work for credit: • Write down the formula • Show numbers in the formula • Circle answer with the proper units

  26. Large and Small Numbers • In electricity, you will work with very large and very small numbers • You must use engineering notation in your work and in your answers • 736 400 = 736.4 x 103 • Like scientific notation, but the exponent is always a power of three (3) • Let’s start by reviewing scientific notation

  27. Scientific Notation • The value is expressed as a number between 1 and 10 which is then multiplied by a power of 10 Powers of 10 • 100 = 1 • 101 = 10 • 102 = 10 x 10 = 100 • 103 = 10 x 10 x 10 = 1,000 • 104 = 10 x 10 x 10 x 10 = 10,000

  28. Negative Powers of 10

  29. Convert to Scientific Notation • Usually you will use your calculator, but you need to understand the process • Multiply by a useful value of 1 • Choose a fraction that moves the decimal so only one digit remains to the left of the decimal point • Because you are multiplying a number by 1, you are not changing its value, only its appearance

  30. Scientific Notation • If you move the decimal point in the number to the left, you are making the number smaller. • To keep the same value, you must multiply by a balancing power of 10

  31. Negative Powers of 10 • If you move the decimal point in the number to the right, you are making the number bigger. • To keep the same value, you must multiply by a negative power of 10

  32. Use Your Calculator • Your calculator can do all of this for you • On a Casio 115-ES • Do SHIFT-MODE-2 to shift the calculator into Line Input/Output • Do SHIFT-MODE-7 to shift the calculator into Scientific Notation • Press 9 for the maximum number of digits available

  33. Other Calculators • On some IT calculators, NORM SCI ENG sets the notation mode. • Numeric notation modes affect only the display of results, and not the accuracy of the values stored in the unit, which remain maximal. • NORM displays results with digits to the left and right of the decimal, as in 123456.78.

  34. Calculator Manual • SCI expresses numbers with one digit to the left of the decimal and the appropriate power of 10, as in 1.2345678x105 (which is the same as 123456.78). • ENG displays results as a number from 1 to 999 times 10 to an integer power. The integer power is always a multiple of 3.

  35. Learn YOUR Calculator – and Use It! • You must be confident with your own calculator • Download the manual and learn how to switch from normal (fixed) to scientific notation to engineering • Once you figure it out, write it down so you can look it up again later on

  36. Examples • Express 0.000 026 in scientific notation. (the space has no meaning) • Set your calculator in Scientific Notation mode • Enter .000 026 • Press the [=] key • The display MAY be 2.6 x 10-5 • What does your display show? Is it correct?

  37. Table 1-5, Column 1, Page 8

  38. Engineering Notation • Write the number using powers of ten. • Move the decimal point left while increasing the exponent or right while decreasing the exponent. • The final exponent must be zero or a number that is evenly divisible by three. • The number itself must be greater than one and less than 1000

  39. Use Your ENG button • Most calculators have an ENG button or mode that automatically switches the displayed answer to Engineering mode – USE IT! • 47,000,000 = 4.7 x 107 (Scientific Notation) = 47 x 106 (Engineering Notation) • 0.000 027 = 2.7 x 10-5 (Scientific Notation) = 27 x 10-6 (Engineering Notation) • 0.605 = 6.05 x 10-1 (Scientific Notation) = 605 x 10-3 (Engineering Notation)

  40. Table 1-5, Column 2, Page 8

  41. Reversing the Process • Example: Express 2.5 x 10-6 in regular decimal form • Set you calculator for Fixed or Normal display • Enter 2.5 [x10x] [ (-) ] 6 [=] • [x10x] might be [EE] or [EXP] • Your result should be: • 0.000 002 5

  42. TI Details • Numbers in scientific notation can be entered in a scientific calculator using the EE key. • Most scientific calculators can be placed in a mode that will automatically convert any decimal number entered into scientific notation or engineering notation.

  43. Practice Now

  44. Calculations with Exponents • When multiplying, you add exponents • (10x10x10)x(10x10) = 10x10x10x10x10 =105 • 103 x 102 = 103+2 = 105 • 6 x 105 x 2 x 102 = 12 x 107 = 120x106 • Use your calculator in Engineering notation to find: • 3.21 x 105 x 12.98 x 107 = • 3.21 [EXP] 5 [x] 12.98 [EXP] 7 [=] 41.67 x 1012 • Note: [EXP] may be [x10X] or [EE] or something else on your calculator • The answer was switched to Engineering Notation and rounded off

  45. Example • Use ( ) around the terms in the denominator • 4.5 [x10x] [ (-) ] 4 [÷] [(] 6 [x10x] 5 [x]7 [x10x] [ (-) ] 8 [)] [ = ] • 1.07 x 10-2 OR 10.71 x 10-3 in [ENG] • Some TI calculators REQUIRE ( ) when dividing in scientific notation

  46. Page 10, Problem 3, 4

  47. Page 10, # 4

  48. Prefixes • Engineers usually replace the power of ten with a prefix • Because all powers of 10 are multiples of 3 in Engineering Notation, we don’t have so many to remember • Some prefixes use Greek letters as symbols • Procedure to use a prefix • 1. Write the quantity in engineering notation. • 2. Replace the power of ten with its prefix.

  49. Prefixes and Symbols

  50. Prefixes and Symbols The prefix symbols Y (yotta), Z (zetta), E (exa), P (peta), T (tera), G (giga), and M (mega) are printed in upper-case letters while all other prefix symbols are printed in lower-case letters

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