1. 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
ET115 DC Electronics - Elberfeld
ET115 DC Electronics - Elberfeld 1

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
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 %
Quizzes………………… %
Unit Exams %
Theory Final %
Lab Final … %

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. 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

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. 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

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. 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

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
Ohm’s Law
Energy and Power 3 6
Series Circuits Exam I 4 7
Parallel Circuits 5 9
Series-Parallel Circuits 6 10
Thevenin’s, Power Exam
Superposition Theorem
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 D Pages

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
= 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

34. Calculator Manual
SCI expresses numbers with one digit to the left of the decimal and the appropriate power of 10, as in x105 (which is the same as ).
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 in scientific notation. (the space has no meaning)
Set your calculator in Scientific Notation mode
Enter
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 Number Scientific Notation 0.0829 V
48,000 Hz
2,200,000 Ω A
7,500 W F
270,000 Ω H

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)
= 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 Number Engineering Notation 0.0829 V
48,000 Hz
2,200,000 Ω A
7,500 W F
270,000 Ω H

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:

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

44. Calculations with Exponents
When multiplying, you add exponents
(10x10x10)x(10x10) = 10x10x10x10x10 =105
103 x 102 = = 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 x 107 =
3.21 [EXP] 5 [x] [EXP] 7 [=] 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 OR x in [ENG]
Some TI calculators REQUIRE ( ) when dividing in scientific notation

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

47. Page 10, # 4
Number
Engineering

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

50. 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

51. 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

52. 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

53. 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

54. 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.

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

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

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

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

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

60. 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 s
9.5 x 10-2 H

61. 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

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

63. 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

64. Unit Conversions
Convert 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

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

66. 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

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

68. 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

69. 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.

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

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

72. 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

73. 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

74. 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 ______________
Scientists do NOT waste time writing down non-significant digits

75. Place Holders 5.40 cm has 3 significant figure
Expressed as meters, the number is m. (and 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

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

77. 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.

78. 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

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

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

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

82. 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.

83. Home Safety
Regular and GFCI (Ground Fault Circuit Interrupter)

84. 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

85. 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.

86. 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.