Chabot ENGR45 – Courtesy of Prof. E. Allen • SJSU CoE MATE-153
LabNotes Rev. Sp07
Writing Assignment - Short Engineering Report
Lab 6. Temperature Dependence of Metal Resistivity
1. Your Firm
Your firm, BEST Copper, fabricates high purity copper wire. You purchase Chinese copper metal
ingots, and form this raw material into copper wire using a hot-drawing process. You produce different
gauges (diameters) of copper wire, which you sell to industrial manufacturers who use it in a variety of
applications, including electrical wiring, power adaptors, power supplies, and motor windings.
2. Your Job
You are a materials quality engineer at the company headquarters, and oversee quality control for the
company plant in the Dalian Economic and Technical Development Zone, China. They periodically
send copper wire samples to you, which you submit to various metallurgical and electrical tests for
quality control. You then prepare reports for the manager of the plant, describing the test and results.
3. The Assignment
Your elemental analysis of one wire sample showed a slightly elevated level of impurities. To determine
if these impurities adversely affect the resistivity, you decide to test the wire using a standard quality
control procedure, which is described in Lab Notes Chapter 6. You then summarize the test and results
in a short engineering report.
For the wire to be usable, both the reference resistivity (at 0°C or 20 °C; state which applies) and the
temperature coefficient of resistivity (α) should equal to commonly accepted values, as determined by
the literature. Be sure to list your references in footnotes or endnotes.
4. The Audience
Your report will go to Zheng You, the plant manager. She is primarily interested in the bottom line; i.e.,
if the wire meets the required specifications. Someone in her position will likely be familiar with basic
engineering concepts, but may or may not fully understand relevant material science concepts which
require specialized knowledge, such as the origin of metal resistivity and Matthiessen’s Rule.
5. The Report
The requirements for the short engineering report, including required sections and some guidelines for
appropriate content, are outlined below.
Be sure to refer to the “Report Formats for MatE 153 Laboratory” and the “Grading Guidelines for
Laboratory Report Temperature Dependence of Metal Resistivity” handouts.
6. Length and Time Guidelines
6 to 11 pages
4 to 6 hours
These are only rough guidelines; your report may be longer or shorter, and you may need more or less
time to complete the assignment.
Cover Letter
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Chabot ENGR45 – Courtesy of Prof. E. Allen • SJSU CoE MATE-153

LabNotes Rev. Sp07
Write a short cover letter, directing the report to the plant manager Zheng You.
o Briefly state the problem, your work, results and recommendations.
Introduction (1 ½ to 3 pages)
 State the purpose of your research.
 Briefly explain any scientific concepts and theories relevant to the experiment, including:
o What resistance, resistivity and mobility are
o How and why a metal’s resistivity varies with temperature
o Matthiessen’s Rule, including the thermal and structural components


Include an appropriate level of detail for your audience.
o There is not enough detail if you simply write that resistivity increases with
temperature without any explanation.
o There is too much detail if you give the quantum mechanical description of
resistance.
Write in your own words.
Experimental Procedure (1 to 2 pages)
 Describe how the experiment was done, in your own words.
 Include an appropriate level of detail for your audience.
 Include an engineering sketch or digital photo of the experimental setup.
o Equipment shown in the sketch or photo should be clearly identified.
o Don’t forget a schematic of the circuit.
Results (2 to 3 pages)
 When stating your results, be specific. For this report, state the relationship between
temperature and resistivity, and other relevant results such as the temperature coefficient of
resistivity  and reference resistivity ρo.
 Remember to include your data and results in properly formatted tables and plots.
 Include some sample calculations to demonstrate how you obtained your results.
Discussion of Results (1 to 2 pages)
 Explain the results. Do they make sense? How do  and ρo compare with the theoretical
values?
 Try to explain any differences between experimental and expected values.
o Describe any sources of error, either from experimental error or differences in
theoretical and experimental conditions.
o Explain how the sources of error affected your results.
Conclusion (1/2 to 1 page)
 Does the material meet the required specifications for ρo and ? (Be sure to list your
literature references sources for ρo and )
 If it does not, explain the source of the difference (materials or processing, or experimental
error).
 Describe corrective actions that could be taken to improve the resistive properties.
References
 List all references you consulted to write this report.
533571185 • pg 2
Chabot ENGR45 – Courtesy of Prof. E. Allen • SJSU CoE MATE-153
LabNotes Rev. Sp07
Appendix A Temperature Coefficient of Resistance for Selected Metals1
TEMPERATURE COEFFICIENTS OF RESISTANCE, AT 20 °C
Material
Element/Alloy
α0 (°C-1)
=============================================
Nickel -------- Element --------- 0.005866
Iron ---------- Element --------- 0.005671
Molybdenum ---- Element --------- 0.004579
Tungsten ------ Element --------- 0.004403
Aluminum ------ Element --------- 0.004308
Copper -------- Element --------- 0.004041
Silver -------- Element --------- 0.003819
Platinum ------ Element --------- 0.003729
Gold ---------- Element --------- 0.003715
Zinc ---------- Element --------- 0.003847
Steel* --------- Alloy ---------- 0.003
Nichrome ------- Alloy ---------- 0.00017
Nichrome V ----- Alloy ---------- 0.00013
Manganin ------- Alloy ------ +/- 0.000015
Constantan ----- Alloy --------- -0.000074
* = Steel alloy at 99.5 percent iron, 0.5 percent carbon
1
http://www.allaboutcircuits.com/vol_1/chpt_12/6.html, Feb 2007
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