Lesson Plan
Course Title
Electronics
Session Title
Conductors and Insulators
Performance Objective
Upon completion of this lesson, the student will be able to describe functional features of
electrical conductors and insulators and select true statements about wire sizes, gauge
numbers, properties of conducting materials, and wire resistance. The student should also be
able to calculate wire diameters, cross-sectional areas, and resistance. This knowledge will be
evidenced by correctly performing the procedures outlined on the assignment sheet and by
scoring 85 percent on the exam.
Specific Objectives
 Match terms associated with conductors and insulators with their definitions
 Distinguish between conductors, semiconductors, and insulators
 Describe four functional features of electrical conductors
 Describe four functional features of electrical insulators
 Name major applications of conductors
 Name types of wire conductors
 Select statements that are true about wire size and gauge numbers
 Select statements that are true about the properties of conducting materials
 Select statements that are true about wire resistance
 Name the desirable properties of wire insulation
 Calculate wire diameters, cross-sectional areas, and resistance
Preparation
TEKS Correlations
This lesson, as published, correlates to the following TEKS. Any changes/alterations to the
activities may result in the elimination of any or all of the TEKS listed.
Electronics
 130.368 (c)
o (6) The student applies the concepts and skills to simulated and actual work
situations. The student is expected to:
(A) measure and calculate resistance, current, voltage, and power in
series, parallel, and complex circuits;
(B) apply electronic theory to generators, electric motors,
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1
and transformers;
(C) design analog and digital circuits using common components; and
(D) demonstrate knowledge of common devices in optoelectronics.
Interdisciplinary Correlations
Advanced Building Maintenance Technology
 130.55 (c)
o (3) The student knows how to interpret electrical drawings, electrical symbols,
schematics, one-line diagrams, and wiring diagrams. The student is expected to:
(A) explain the basic layout of an electrical drawing;
(B) identify the common symbols used on electrical drawings;
(C) read equipment schedules found on electrical drawings; and
(D) describe the type of information included in electrical specifications.
o (7) The student installs and maintains electrical devices and knows wiring
techniques common to commercial and industrial facilities. The student
is expected to:
(A) describe how to determine electrical service requirements for
commercial and industrial facilities;
(B) select the proper wiring methods for various commercial and
industrial facilities;
(D) compute branch circuit loads and explain their installation
requirements; and
(E) explain the types and purposes of equipment grounding conductors.
Algebra I
 111.39 (c)
o (1) Mathematical process standards. The student uses mathematical processes
to acquire and demonstrate mathematical understanding. The student
is expected to:
(A) apply mathematics to problems arising in everyday life, society, and
the workplace;
(B) use a problem-solving model that incorporates analyzing given
information, formulating a plan or strategy, determining a solution,
justifying the solution, and evaluating the problem-solving process and
the reasonableness of the solution;
(C) select tools, including real objects, manipulatives, paper and pencil,
and technology as appropriate, and techniques, including mental math,
estimation, and number sense as appropriate, to solve problems;
(D) communicate mathematical ideas, reasoning, and their implications
using multiple representations, including symbols, diagrams, graphs, and
language as appropriate;
(E) create and use representations to organize, record, and communicate
mathematical ideas;
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2
(F) analyze mathematical relationships to connect and communicate
mathematical ideas; and
(G) display, explain, and justify mathematical ideas and arguments using
precise mathematical language in written or oral communication.
Electrical Technology
 130.56 (c)
o (9) The student learns the types and applications of conductors and wiring
techniques. The student is expected to:
(A) explain the various sizes and gauges of wire in accordance with
American Wire Gauge standards;
(B) identify insulation and jacket types according to conditions
and applications;
(C) describe voltage ratings of conductors and cables;
(D) read and identify markings on conductors and cables;
(E) use the tables in the National Electrical Code to determine the
ampacity of a conductor;
(F) state the purpose of stranded wire;
(G) state the purpose of compressed conductors;
(H) describe the different materials from which conductors are
made; and
(I) describe the different types of conductor insulation.
Occupational Correlation
Reference
O*Net www.onetonline.org
Job Title
Electricians
O*Net Number
47-2111.00
Reported Job Titles
Electrician, Maintenance Electrician, Journeyman Electrician, Inside Wireman, Control
Electrician, Electrician Technician, Industrial Electrician, Journeyman Wireman
Tasks



Maintain current electrician's license or identification card to meet
governmental regulations.
Connect wires to circuit breakers, transformers, or other components.
Repair or replace wiring, equipment, or fixtures, using hand tools or power tools.
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3







Assemble, install, test, or maintain electrical or electronic wiring, equipment,
appliances, apparatus, or fixtures, using hand tools or power tools.
Test electrical systems or continuity of circuits in electrical wiring, equipment, or
fixtures, using testing devices, such as ohmmeters, voltmeters, or oscilloscopes, to
ensure compatibility and safety of system.
Use a variety of tools or equipment, such as power construction equipment, measuring
devices, power tools, and testing equipment, such as oscilloscopes, ammeters, or
test lamps.
Plan layout and installation of electrical wiring, equipment, or fixtures, based on job
specifications and local codes.
Inspect electrical systems, equipment, or components to identify hazards, defects, or
the need for adjustment or repair, and to ensure compliance with codes.
Direct or train workers to install, maintain, or repair electrical wiring, equipment,
or fixtures.
Diagnose malfunctioning systems, apparatus, or components, using test equipment and
hand tools to locate the cause of a breakdown and correct the problem.
Soft Skills
Troubleshooting/ Active Listening/ Critical Thinking/ Operation Monitoring/ Quality Control
Analysis/ Active Learning/ Complex Problem Solving/ Judgment and Decision Making
References
 Buchla, D. and Floyd, T. (2005). The science of electronics DC/AC. Upper Saddle River, NJ:
Prentice Hall.
 Floyd, T. (1993). Principles of electric circuits: electron flow version. Don Mills, Ontario:
Macmillian Publishing Co.
 Robertson, L. (1980). Basic electronics 1. Stillwater, OK: Mid-American Vocational
Curriculum Consortium, Inc.
Instructional Aids
 Conductors and Insulators slide presentation and notes
 Activity #1 – Calculate Wire Diameters, Cross-Sectional Areas, and Resistance
 Activity #1 – Calculate Wire Diameters, Cross-Sectional Areas, and Resistance Key
 Conductors and Insulators Exam
 Conductors and Insulators Exam Key
Materials Needed
 Pencils and paper
 Electronic wire materials
 Dry erase markers
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4

Dry board eraser
Equipment Needed
 Computer
 Overhead projector and screen
 Whiteboard
 Breadboards and leads
 Power supplies
 Multimeters
 Calculator
Learner Preparation
 Complete assignment activity.
 Student watches Conductors and Insulators slide presentation and takes notes
on material.
Introduction
Introduction (LSI Quadrant I)
Say
We need a way to deliver electrical energy over both large and small distances.
Ask
What do we use?
What are the characteristics of the things we use?
Say
Today, we are going to explore the world of wire sizes, gauge number, and wire resistance.
Outline
Teachers can use the slide presentation and notes, and handouts in conjunction with the
following outline.
Outline (LSI Quadrant II)
I.
Introduction
A. Overview presentation with students.
B. Review terms and definitions with students.
C. Terms are important because they form the
foundation for understanding the properties of
conductors and how resistance is calculated.
Teacher Notes
Begin Conductors and
Insulators slide presentation.
(Slides 1-5)
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5
D. Review conducting and insulating materials from
the previous lesson to bridge from one lesson to
the next and illustrate the concepts of resistivity
and conductivity.
II.
Wire Types and Applications
A. It is important to note that wires are used to
deliver electricity where it is needed and only
where it is needed.
B. Point out different examples of conductors from
the tiny traces on circuit boards to the large
overhead power lines and note the differences
in size.
C. Show multi-meter, scope leads, and shielded
wires where available.
(Slides 6-8)
The more examples of types
of conductors the better.
III.
Wire Resistance
(Slides 9-11)
A. The first slide (9) is a verbal description of the
relationship between wire resistance and the
physical characteristics of the wire like length
and cross-sectional area.
B. The next slide (10) introduces the mathematical
formula used to calculate wire resistance.
C. Relate the symbols to the physical characteristics
already discussed.
D. Note that an ideal wire has zero resistance, while
an actual wire has a small but measurable
resistance that can cause problems like power
and voltage loss (slide 11 demonstrates this
concept).
IV.
Wire gauge values
A. Wires have discrete size values measured in
cross-sectional area.
B. Wire gauge is the term that identifies the
particular size.
C. American Standard Wire Gauge number
describes how big the wire is.
D. The bigger the number, the smaller the wire.
E. Review values for copper wire, but any type of
wire with a particular diameter has a particular
(Slides 12-14)
Since any type of wire with a
particular diameter has a
Copyright © Texas Education Agency, 2013. All rights reserved.
6
wire gauge.
F. Review the charts on slides 12-14.
particular wire gauge, the
only factor here that
depends on the material is
the weight.
The chart on slide 12 is
relatively small, so the next
two slides give the chart in a
larger, more readable
format. For student use, wire
gauge values can be printed
and handed out.
(Slide 15)
V.
Properties of Conducting Materials
A. This slide shows other important properties of
conducting materials.
B. The most important property shown is
specific resistance.
C. The most common conductor is copper, so that
will be the most common specific resistance
value used.
VI.
Calculation Examples
A. Demonstrate the first example shown on slide 16
on the board or overhead.
B. The example problems on slide 17 are for
students to calculate.
C. Make more examples so students can get plenty
of practice.
D. This is a demonstration of the practical use of
algebra and mathematics in the workplace.
(Slides 16-17)
VII. Desirable Properties of Wire Insulation
A. Insulation is just as important as conductivity.
B. Insulation protects both people and
electrical equipment.
C. You do not want insulation to fail or breakdown.
(Slides 18-19)
VIII. Presentation Summary
Slide 20
Note that for some
examples, students will need
to rearrange the formula.
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7
IX. Teacher Demonstrations
A. Calculate wire size and gauge number.
B. Show the difference between solid and
stranded wire.
Activity #1 – Calculate Wire
Diameters, Cross-Sectional
Areas, and Resistance
Application
Guided Practice (LSI Quadrant III)
The teacher will use materials as listed in the lab activities to instruct students how to read,
measure, and record data needed. The students will observe, ask questions, and analyze the
demonstration to be presented by the teacher.
Independent Practice (LSI Quadrant III)
The student will try to replicate the activities. The student will answer the discussion questions
on the activity sheets and turn in for evaluation.
Summary
Review (LSI Quadrants I and IV)
Review the information on the Conductors and Insulators Exam with the students.
Evaluation
Informal Assessment (LSI Quadrant III)
The teacher will monitor each student or small group as they work to complete the
assignments. If re-teach is needed on any information or procedure, all those involved will stop
and participate in the re-teach.
Formal Assessment (LSI Quadrant III, IV)
The student will be assessed by the accuracy of the completed assignment. Use the Activity #1 –
Calculate Wire Diameters, Cross-sectional Areas, and Resistance Key to grade the activity.
The teacher will divide the final assessment into two parts:
1. a measurement test of a series of exercises using the multimeter to measure
wire resistance accurately, and
2. a formal exam (use the Conductors and Insulators Exam and Key).
Extension
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8
Extension/Enrichment (LSI Quadrant IV)
 The use of the multimeter to measure resistance accurately becomes a vital part of the
technical, problem-solving skills needed in the world of work.
 Thinking through a problem to arrive at the answer and the persistency to work past
their frustrations tempers their character.
 There are points in the assignment experience where the student takes some part in
leadership skills; leading or following creates a sense of accomplishment that adds to
the students’ character. Cognitive and leadership skills go hand in hand with solving
life’s roadblocks.
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9
Name:_________________________________Class:__________Date:___/___/___
Conductors and Insulators
Activity #1 – Calculate Wire Diameters, Cross-Sectional Areas, and Resistance
1. The diameter of a copper wire is .040 inch.
A. What is the circular mil area of the wire? ___________________
B. What is the AWG size? __________________________________
C. What is the resistance of a 100 ft length? ___________________
2. As the AWG number of wire increases,
A. The diameter of the wire __________ (increases/decreases)
B. The cross-sectional area of the wire __________ (increases/decreases)
C. The resistance __________ (increases/decreases)
D. The voltage (IR) drop of the wire in the circuit __________ (increases/decreases)
3. Circular mil ohm per foot (cmil-ohm/ft) represents: (circle one)
A. The breakdown voltage of an insulator
B. The Resistivity of a semiconductor
C. The Resistivity of a wire conductor
D. The cross-sectional area of a wire conductor
4. The symbol ρ (Greek letter “rho”) stands for: (circle one)
A. The cross-sectional area of a conductor
B. The resistivity of conducting material
C. The breakdown voltage of a dielectric
D. The temperature coefficient of conducting material
5. The symbol α (Greek letter “alpha”) stands for: (circle one)
A. The temperature coefficient of conducting materials
B. The specific resistance of conducting material
C. The dielectric strength of insulators
D. The resistivity of semiconductors
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10
Name:_________________________________Class:__________Date:___/___/___
6. Calculate the total resistance (to nearest .1 ohm) of the following wires (at room
temperature):
A. 1000 ft of No. 14 copper wire
R= _______________
B. 250 ft of No. 26 copper wire
R= _______________
C. 511 ft or No. 20 copper wire
R= _______________
D. 100 ft of aluminum wire w/ diameter of .040 in.
R= _______________
E. 1500 ft of silver wire with a diameter of .003 in.
R= ______________
7. A twin-lead cable of No. 20 copper wire is short-circuited at one end. The resistance
reading at the open end is 2 ohms. What is the cable length in feet at room temperature?
_________________________ feet
8. A coil is wound with 3000 turns of No. 18 copper wire. If the average amount of wire in a
turn is 4 in.,
A. How much is the total resistance of the wire? __________ ohms
B. What will be the resistance if No. 26 copper wire is used instead? __________
ohms
9. If 200 ft of wire has to be used, what is the smallest size copper wire that will limit the line
drop of 5v, with 120v applied with a 6A load? _______________________
10. Calculate the following for the circuit below:
A. I = ____________
B. RL = __________
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11
Name:_________________________________Class:__________Date:___/___/___
Conductors and Insulators
Activity #1 – Calculate Wire Diameters, Cross-Sectional Areas, and Resistance
Key
1. The diameter of a copper wire is .040 in.
A. What is the circular mil area of the wire? _1600 cmils_________
B. What is the AWG size? ___No. 18_______________________
C. What is the resistance of a 100 ft length? ___0.65 ohms__________
2. As the AWG number of wire increases,
A. The diameter of the wire __________ (increases/decreases)
B. The cross-sectional area of the wire __________ (increases/decreases)
C. The resistance __________ (increases/decreases)
D. The voltage (IR) drop of the wire in the circuit __________ (increases/decreases)
3. Circular mil ohm per ft (cmil-ohm/ft) represents: (circle one)
A. The breakdown voltage of an insulator
B. The Resistivity of a semiconductor
C. The Resistivity of a wire conductor
D. The cross-sectional area of a wire conductor
4. The symbol ρ (Greek letter “rho”) stands for: (circle one)
A. The cross-sectional area of a conductor
B. The resistivity of conducting material
C. The breakdown voltage of a dielectric
D. The temperature coefficient of conducting material
5. The symbol α (Greek letter “alpha”) stands for: (circle one)
A. The temperature coefficient of conducting materials
B. The specific resistance of conducting material
C. The dielectric strength of insulators
D. The resistivity of semiconductors
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12
Name_________________________________Class:__________Date:___/___/___
6. Calculate the total resistance (to nearest .1 ohm) of the following wires (at room
temperature):
A. 1000 ft of No. 14 copper wire
R= ___2.6 ohms___
B. 250 ft of No. 26 copper wire
R= ___10.4 ohms__
C. 511 ft or No. 20 copper wire
R= ___5.3 ohms__
D. 100 ft of aluminum wire w/ diameter of .040 in.
R= ___1.1 ohms___
E. 1500 ft of silver wire with a diameter of .003 in.
R= __1633.3 ohms
7. A twin-lead cable of No. 20 copper wire is short-circuited at one end. The resistance
reading at the open end is 2 ohms. What is the cable length in ft at room temperature?
_______100____________ ft
8. A coil is wound with 3000 turns of No. 18 copper wire. If the average amount of wire in a
turn is 4 in.,
A. How much is the total resistance of the wire? ____6.51________ ohms
B. What will be the resistance if No. 26 copper wire is used instead? 41.62 ohms
9. If 200 ft of wire has to be used, what is the smallest size copper wire that will limit the line
drop of 5v, with 120v applied with a 6A load? ___No. 16 wire____
10. Calculate the following for the circuit below:
A. I = ___30 amps__
B. RL = _3.18 ohms_
Copyright © Texas Education Agency, 2013. All rights reserved.
13
Name:_________________________________Class:__________Date:___/___/___
Conductors and Insulators
Exam
Match the terms to the correct definitions.
1. Mil
A A material having relatively high
resistance (when room temperature)
whose electrical characteristics can be
changed and controlled by various
techniques, such as adding other
elements called “impurities.”
2. Dielectric
B The cross-sectional area of a wire
calculated by squaring the wire diameter
in mils
3. Conductivity
C One thousandth of an inch
4. Circular mil area
D A material of very high resistance that
is capable of holding or storing an
electrical charge.
5. Semiconductor
E The capacity of a conducting rod of unit
length and cross-sectional area to allow
electrical current flow.
6. Which of the following is a type of insulator?
A Tungsten
B Silicon
C Nickel
D Shellac
7. Which of the following is a type of semiconductor?
A Tungsten
B Silicon
C Nickel
D Shellac
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14
Name:_________________________________Class:__________Date:___/___/___
8. Which of the following is a type of conductor?
A Paper
B Germanium
C Copper
D Glass
9. Which of the following is a type of semiconductor?
A Paper
B Germanium
C Copper
D Glass
10. Which of the following is NOT a type of conductor?
A Iron
B Tungsten
C Copper
D Glass
11. Which of the following is NOT a type of insulator?
A Air or vacuum
B Silicon
C Rubber
D Glass
12. Select the true statement about wire sizes and gauge numbers.
A The American Standard Wire Gauge is used to determine wire resistivity.
B “Circular mil” is the unit used to describe the diameter of a conducting wire.
C The higher the gauge number of a wire, the lower its resistance.
D The higher the gauge number of a wire, the smaller its wire diameter.
13. Select the false statement about wire sizes and gauge numbers.
A The cross-sectional area of a conducting wire is measured in square inches.
B “Circular mil” is the unit used to describe the diameter squared of a
conducting wire.
C The higher the gauge number of a wire, the higher its resistance.
D The American Standard Wire Gauge is used to check wire sizes.
14. Select the true statement about the properties of conducting materials.
A The symbol for resistivity is the Greek letter “alpha” (α).
B Resistivity of wire conductors is expressed in mm2-ohm per foot.
C Specific resistance and resistivity refer to the same property.
D The resistivity of conducting materials does not change with temperature
Copyright © Texas Education Agency, 2013. All rights reserved.
15
Name:_________________________________Class:__________Date:___/___/___
GAUGE
NO.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
DIAMETER CIRCULAR- OHMS
MILS
MIL AREA PER
1,000 FT
OF
COPPER
WIRE AT
25ºC*
289.3
257.6
229.4
204.3
181.9
162.0
144.3
128.5
114.4
101.9
90.74
80.81
71.96
64.08
57.07
50.82
45.26
40.30
35.89
31.96
83,690
66,370
52,640
41,740
33,100
26,250
20,820
16,510
13,090
10,380
8,234
6,530
5,178
4,107
3,257
2,583
2,048
1,524
1,288
1,022
0.1264
0.1593
0.2009
0.2533
0.3195
0.4028
0.5080
0.6405
0.8077
1.018
1.284
1.619
2.042
2.575
3.247
4.094
5.163
6.510
8.210
10.35
GAUGE
NO.
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
DIAMETER CIRCULAR- OHMS
MILS
MIL AREA PER
1,000 FT
OF
COPPER
WIRE AT
25ºC*
28.46
25.35
22.57
20.10
17.90
15.94
14.20
12.64
11.26
10.03
8.928
7.950
7.080
6.305
5.615
5.000
4.453
3.965
3.531
3.145
810.1
642.4
509.5
404.0
320.4
254.1
201.5
159.8
126.7
100.5
79.70
63.21
50.13
39.75
31.52
25.00
19.83
15.72
12.47
9.88
13.05
16.46
20.76
26.17
33.00
41.62
52.48
66.17
83.44
105.2
132.7
167.3
211.0
266.0
335.0
423.0
533.4
672.6
848.1
1,069
20 TO 25ºC or 68 to 77ºF is considered average room temperature.
15. Refer to the standard copper wire gauge table, and select the false statement
about wire sizes and gauge number.
A The diameter of No. 19 copper wire is 35.89 mils.
B The diameter of No. 21 copper wire is 0.028 in.
C The cross-sectional area of No. 14 copper wire is 64.08 cmils.
D The resistance of 100 ft of No. 26 copper wire is 4.2 ohms.
16. Refer to the standard copper wire gauge table, and select the true statement
about wire sizes and gauge number.
A The diameter of No. 36 copper wire is 5 mils.
B The diameter of No. 10 copper wire is 0.091 in.
C The cross-sectional area of No. 24 copper wire is 320.4 cmils.
D The resistance of 100 ft of No. 6 copper wire is 0.4028 ohms.
Copyright © Texas Education Agency, 2013. All rights reserved.
16
Name:_________________________________Class:__________Date:___/___/___
Conductors and Insulators
Exam Key
Match the terms to the correct definitions.
1. Mil
C
A A material having relatively high
resistance (when room temperature)
whose electrical characteristics can be
changed and controlled by various
techniques, such as adding other
elements called “impurities.”
2. Dielectric
D
B The cross-sectional area of a wire
calculated by squaring the wire diameter
in mils
3. Conductivity
E
C One thousandth of an inch
4. Circular mil
area
B
D A material of very high resistance that
is capable of holding or storing an
electrical charge.
5. Semiconductor
A
E The capacity of a conducting rod of unit
length and cross-sectional area to allow
electrical current flow.
6. Which of the following is a type of insulator?
A Tungsten
B Silicon
C Nickel
D Shellac
7. Which of the following is a type of semiconductor?
A Tungsten
B Silicon
C Nickel
D Shellac
Copyright © Texas Education Agency, 2013. All rights reserved.
17
Name:_________________________________Class:__________Date:___/___/___
8. Which of the following is a type of conductor?
A Paper
B Germanium
C Copper
D Glass
9. Which of the following is a type of semiconductor?
A Paper
B Germanium
C Copper
D Glass
10. Which of the following is NOT a type of conductor?
A Iron
B Tungsten
C Copper
D Glass
11. Which of the following is NOT a type of insulator?
A Air or vacuum
B Silicon
C Rubber
D Glass
12. Select the true statement about wire sizes and gauge numbers.
A The American Standard Wire Gauge is used to determine wire resistivity.
B “Circular mil” is the unit used to describe the diameter of a conducting wire.
C The higher the gauge number of a wire, the lower its resistance.
D The higher the gauge number of a wire, the smaller its wire diameter.
13. Select the false statement about wire sizes and gauge numbers.
A The cross-sectional area of a conducting wire is measured in square inches.
B “Circular mil” is the unit used to describe the diameter squared of a
conducting wire.
C The higher the gauge number of a wire, the higher its resistance.
D The American Standard Wire Gauge is used to check wire sizes.
14. Select the true statement about the properties of conducting materials.
A The symbol for resistivity is the Greek letter “alpha” (α).
B Resistivity of wire conductors is expressed in mm2-ohm per ft.
C Specific resistance and resistivity refer to the same property.
D The resistivity of conducting materials does not change with temperature.
Copyright © Texas Education Agency, 2013. All rights reserved.
18
Name:_________________________________Class:__________Date:___/___/___
GAUGE
NO.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
DIAMETER
MILS
CIRCULARMIL AREA
OHMS
PER
1,000 FT
OF
COPPER
WIRE AT
25ºC*
289.3
257.6
229.4
204.3
181.9
162.0
144.3
128.5
114.4
101.9
90.74
80.81
71.96
64.08
57.07
50.82
45.26
40.30
35.89
31.96
83,690
66,370
52,640
41,740
33,100
26,250
20,820
16,510
13,090
10,380
8,234
6,530
5,178
4,107
3,257
2,583
2,048
1,524
1,288
1,022
0.1264
0.1593
0.2009
0.2533
0.3195
0.4028
0.5080
0.6405
0.8077
1.018
1.284
1.619
2.042
2.575
3.247
4.094
5.163
6.510
8.210
10.35
GAUGE
NO.
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
DIAMETER
MILS
CIRCULARMIL AREA
OHMS
PER
1,000 FT
OF
COPPER
WIRE AT
25ºC*
28.46
25.35
22.57
20.10
17.90
15.94
14.20
12.64
11.26
10.03
8.928
7.950
7.080
6.305
5.615
5.000
4.453
3.965
3.531
3.145
810.1
642.4
509.5
404.0
320.4
254.1
201.5
159.8
126.7
100.5
79.70
63.21
50.13
39.75
31.52
25.00
19.83
15.72
12.47
9.88
13.05
16.46
20.76
26.17
33.00
41.62
52.48
66.17
83.44
105.2
132.7
167.3
211.0
266.0
335.0
423.0
533.4
672.6
848.1
1,069
20 TO 25ºC or 68 to 77ºF is considered average room temperature.
15. Refer to the standard copper wire gauge table, and select the false statement
about wire sizes and gauge number.
A The diameter of No. 19 copper wire is 35.89 mils
B The diameter of No. 21 copper wire is 0.028 in.
C The cross-sectional area of No. 14 copper wire is 64.08 cmils
D The resistance of 100 ft of No. 26 copper wire is 4.2 ohms
16. Refer to the standard copper wire gauge table, and select the true statement
about wire sizes and gauge number.
A The diameter of No. 36 copper wire is 5 mils
B The diameter of No. 10 copper wire is 0.091 in.
C The cross-sectional area of No. 24 copper wire is 320.4 cmils
D The resistance of 100 ft of No. 6 copper wire is 0.4028 ohms
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