Unit One: Quantities, Units, and Electrical Safety 4/21/2017 4/21/2017 ET115 DC Electronics Unit One: Quantities, Units, and Electrical Safety John Elberfeld JElberfeld@itt-tech.edu WWW.J-Elberfeld.com ET115 DC Electronics - Elberfeld ET115 DC Electronics - Elberfeld 1

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

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

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.

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.

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.

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.

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

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

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!

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.)

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

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

Homework 25% 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

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

Lab Exercises 30% 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

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

Theory Final 15% 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

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!

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

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.

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.

Reading Assignment Read and study Chapter 1: Quantities and Units Pages 1-16 Utility Voltages – Appendix D Pages 323-324

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

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

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

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

Negative Powers of 10

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

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

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

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

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.

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.

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

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?

Table 1-5, Column 1, Page 8 Number Scientific Notation 0.0829 V 48,000 Hz 2,200,000 Ω 0.000 015 A 7,500 W 0.000 000 033 F 270,000 Ω 0.000 010 H

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

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)

Table 1-5, Column 2, Page 8 Number Engineering Notation 0.0829 V 48,000 Hz 2,200,000 Ω 0.000 015 A 7,500 W 0.000 000 033 F 270,000 Ω 0.000 010 H

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

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.

Practice Now Number Regular Decimal Form 8.29 x 10-2 48.0 x 103

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

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

Page 10, Problem 3, 4 Number Engineering (3.6x104)(8.8x10-4)

Page 10, # 4 Number Engineering

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.

Prefixes and Symbols Power of 10 Prefix Symbol 10-12 pico p 10-9 nano 10-6 micro µ 10-3 milli m

Prefixes and Symbols Power of 10 Prefix Symbol 103 kilo k 106 mega M 109 giga G 1012 tera T 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

Units In electronics, measurements always have a number and a unit Units are a vital part of your answer Answers to problems include a number in Engineering Notation, with the proper prefix substituted for the power of 10, and the correct unit

Seven Basic Units SI Fundamental Units Quantity Unit Symbol Length Meter m Mass Kilogram kg Time Second s Electric current ampere A Temperature Kelvin K Luminous Intensity Candela cd Amount of substance Mole mol

Electrical Units SI Fundamental Units Quantity Symbol Unit Charge Q coulomb C Current I ampere A Energy - Work W joule J Power P watt Resistance R ohm Ω Voltage V volt Conductance G siemens S Capacitance farad F Frequency f Hertz Hz Inductance Henry H

Capitalization Unit symbols are printed in lower-case letters except that the symbol or the first letter of the symbol is an upper-case letter when the name of the unit is derived from the name of a person (Except liter = L, not l) When spelled out in full, unit names are treated like ordinary English nouns. Thus the names of all units start with a lower-case letter, except at the beginning of a sentence or in capitalized material such as a title.

Practice Quantity Unit of Measurement resistance Ohm current voltage energy power conductance charge

More Practice Unit Symbol for Unit Quantity measured ohm Ω volt watt ampere coulomb joule siemens

Example 106=M 103=k 10-3 = m 10-6 = μ 10-9 = n If your calculator displays 5.678 x 106, the equivalent metric value is: Replace the power of 10 with the symbol Because 106 = M 5.678 x 106 = 5.678 M or (round off) 5.68 M (Most times a unit is REQUIRED!)

Table 1-5, Column 3, Page 8 Number Metric Value 0.0829 V 82.9 mV 48,000 Hz 2,200,000 Ω 0.000 015 A 7,500 W 0.000 000 033 F 270,000 Ω 0.000 010 H

Table 1-6, Page 8 Metric Value Engineering Notation 100 pF 100 x 10-12 F 12 kV 85.0 μA 50 GHz 33 kΩ 250 mV 7.8 ns 2.0 MΩ

Page 22, Problem 17 Quantity Engineering Prefix 1.24 x10-6 A 1.24 μA 4.7 x 104 Hz 3.3 x 10-8 F 2.2 x 10-12 s 9.5 x 10-2 H

Page 10, Problem 1 kilowatt 103 W kW milliampere picofarad nanosecond Metric prefix and unit Exponent expression and unit symbol Prefix and unit kilowatt 103 W kW milliampere picofarad nanosecond megohm microhenry

Page 10, Problem 2 Megawatt nA μJ mV kΩ GHz MW Abbreviation Full written expression MW Megawatt nA μJ mV kΩ GHz

Unit Conversions To convert units, multiply by a useful value of 1 Because 1 foot = 12 inches, then: The top and bottom at the same

Unit Conversions Convert 0.00058 microvolts (μV) to the equivalent picovolts (pV). Do NOT put in values for μ as these values cancel Keep the “p” as is This is the “chain” rule used in advanced courses

Another Method The books suggests moving the decimal point Let your calculator do the work Enter 0.00058 x 10-6 and hit the equal sign and [ENG] to get: 580 x 10-12 Since 10-12 = p, we get 0.00058 microvolts = 580 pV Entering [ENG] again or [SHIFT] [Eng] moves to another unit

Example Convert .005 A to μA Enter .005 and press [=] to get: 5 x 10-3 Press [ENG] again to get: 5000 x 10-6 = 5000 μA

Conversions Value Conversion 3,200 μW W 5,000 kV V 10 MW kW 1 ma μa mV 0.02 kΩ MΩ 155 mW

Measured Numbers Any time you make a measurement, the recorded data is never perfect Every measurement has some amount of error in it – always Accurate measurements are measurements that are close to the true or accepted value Precise measurements are consistently close to each other

Measurements } Experimental uncertainty is part of all measurements. Error Experimental uncertainty is part of all measurements. Error is the difference between the true or best accepted value and the measured value. Accuracy is an indication of the range of error in a measurement Precision is a measure of repeatability Error, Accuracy, and Precision . Precise, but not accurate.

Precision and Accuracy Precise and accurate Accurate only Precise only Neither Accurate nor precise

Meter Measurements Digital meters do not depend on the user’s judgment We all see 1.55 VDC and 47.5 Ω

DMM You will use Digital Multi-Meters (DMM) in class On the job, you might have to deal with analog meters Digital meters still estimate the last digit

Significant Figures Every non-zero number you measure, including the one estimated digit, is significant If you measure a “0” to the right of a number, it is significant 0s that are place holders are not significant (to the left of all other digits) You measure the width of a credit card as 5.40 cm. Your best estimate is NOT 5.41 cm or 5.39 cm. The 0 is measured and significant

Significant Figures When measurements are written in scientific notation, every digit in the number is significant All the digits except the right most digit are certain. Which digits are significant in: 3.450 x 108______________ 4.87 x 10 -4 ______________ Scientists do NOT waste time writing down non-significant digits

Place Holders 5.40 cm has 3 significant figure Expressed as meters, the number is 0.0540 m. (and 0.0000540 km) There are still only three digits that you measured, so there are 3 significant figures. Scientist conserve energy. They don’t write 0s at the end of a number unless they are measured and so significant

Examples State the number of significant digits: 1.00 x 103 _________ 0.0057 ____________ 1502.0 ______________ 0.000036 _____________ 0.105 ___________ 2.6 x 102 __________

Calculations From now on, most of your calculations will be done using scientific notation and significant figures Believe it or not, it can make your life easier! Trust Me!! Many rules apply, but for now, THREE significant figures is a good compromise.

Rounding Off You keep all digits in all calculations until your final answer You round off your final answer to the correct number of significant figures In this class, usually THREE significant figures is sufficient

Rounding Rules If the digits dropped are greater than 5, like 698 or 501 increase the last retained digit by 1. 13.1698 = 13.2 23.4501 = 23.5 If the digit dropped is less than 5, do not change the last retained digit. 34.456 = 34 33.533 = 33.5

Round to Even Rule If the digits dropped are 50000…., increase the last retained digit if it makes it even, otherwise do not. 12.345 = 12.34 12.355 = 12.36 Note: 12.3451 = 12.35 Example 1-22 (e) is wrong in the text.

Examples Switch to Engineering notation and round to 3 significant figures Use the “round-to-even” rule 50,505 ______________ 220.45 ______________ 4646 ______________ 10.99 ______________ 1.005 ______________

Safety Suggestions Do not work alone, or when you are drowsy. Wear rubber-soled shoes and stand on insulated mats if floor is conductive Wear safety glasses when clipping wires or soldering. Know the potential hazards of the equipment you are working on; check equipment and power cords frequently. Avoid all contact with energized circuits; even low voltage circuits. Know the location of power shutoff and fire extinguishers. Don’t have food or drinks in the laboratory or work area.

Home Safety Regular and GFCI (Ground Fault Circuit Interrupter)

Built-in Protection In a “good” circuit, the current coming out of the socket from the black or “hot” wire is matched by the current returning to the white or “neutral” wire The GFCI stops all current flow if there is not a perfect match, assuming some of the missing current is going through YOU

Chapter Summary Scientific notation is a method for expressing very large and very small numbers as a number between one and ten (one digit to left of decimal point) times a power of ten. Engineering notation is a form of scientific notation in which quantities are expressed with one, two, or three digits to the left of the decimal point times a power of ten that is a multiple of three.

Chapter Summary Metric prefixes are symbols used to represent powers of ten that are multiples of three. The uncertainty of a measured quantity depends on the accuracy and precision of the measurement. The number of significant digits in the result of a mathematical operation should never exceed the significant digits in the original numbers.