Engineering 45
R = L/A
Lab-02 Sp12 /

Lab Data Sheet – Lab-02

Goal

To measure and study the electrical resistivity & V-I characteristics of various metal and alloy wire specimens – including the impact ofspecimen size (length, thickness).

Lab Logistics

Note: Only two students needed per team; switch roles after measuring half of the specimens

Experimenter (1st half):
Recorder: (1st half):
Date:
Equipment Used (maker, model, and serial no. if available)

Directions

  1. Instruments & Supplies
  • DMMand Red/Black Measurement leads
  • Alligator Clip Leads
  • Dial Calipers; 0.001” (1 mil resolution or Digital Micrometer; 0.0001, 100 μ-in resolution)
  • Resistivity Test-Specimens:

No. / Specimen
1 / Copper
2 / Brass
3 / Monel 400 (Thick)
4 / 80-20 Nichrome (Long)
5 / 80-20 Nichrome (Short)
6 / Nichrome - Chromel C (Thin)
7 / Aluminum 1100
8 / Carbon Steel 1008 (Soft/Ox)
9 / Stainless Steel 304 (Soft)
10 / Stainless Steel 316L (Hard)
11 / Monel 400 (Thin)
  1. Go to the side counter collect a “bread board” anda Current Limiting resistor, R, required to construct the circuit shown in Figure 1.
  • The resistor, R, should be in the Range of 100-200 Ω
  1. Prior to the start of the Test, Measure:
  • The Specimen Diameter with the Calipers at Three locations
  • If a Micrometer is available, the Micrometer may be used for diameter measurements
  • The Value of the current Limiting Resistor with DMM
  1. Note on the Specimen Label the specimen LENGTH.
  2. Determine the length of the new 5 specimens - by either
  • Measuring andsubtracting the wire length remaining in the spool from the original length, or by
  • Counting the number of turns in the coil and measuring theiraverage diameter.
  1. For Various supply voltages complete Table 1thruTable 11. For Each Specimen make Measurement PAIRS :
  • V, the potential across it (volts)
  • I, the current thru it (amps or milliamps)

Note that measurements must be made in ORDERED PAIRS. That is, consider the Current, I, as a function of the Potential, V → I = f(V). Proceed as follows:

  • First set the approximate Voltage Level using the Power Supply Knob
  • Make NO knob adjustments until the accompanying Current measurement is complete
  • Then precisely measure to at least three (3) significant figures the electrical potential (voltage) using the DMM VoltMeter function
  • Finally measure to at least three (3) significant figures the electrical current using the DMM AmMeter function
  • Only now can the Power Supply Knob be adjusted for the next Voltage level.
  1. Write any particular run observations or comments in the bottom section of the Table
  1. Return all lab hardware to the “as-found” condition
  1. Reduce the Data by completing the Resistivity Calculationsin Table 12.
  1. On your report, please elaborate on the reasons for the differences observed in the various metals and alloys, and any probable physical cause(s) – i.e., composition, structure, heat treatment -soft vs hard tempered, etc. and/or experimental errors

Figure 1 Rspecimen= V/ITest Circuit. R = 100-200 Ω

Raw Data and Calculations

Table 1 – COPPERSpecimen#1 Resistivity Measurements

Current Limiter; Ractual =
Specimen Length =

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 2 – BRASS (70Cu-30Zn) Specimen#2Resistivity Measurements

Ractual =
Specimen Length =

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 3 – MONEL400 (THICK)Specimen#3Resistivity Measurements

Ractual =
Specimen Length =

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 4 – NiChrome 80-20 (LONG); Specimen #4Resistivity Measurements

Ractual =
Specimen Length =

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 5– NiChrome 80-20 (SHORT) Specimen #5Resistivity Measurements

Ractual =
Specimen Length =

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 6 – NiChrome – Chromel C (THIN); Specimen #6 Resistivity Measurements

Ractual =
Specimen Length* =

* Need to measure (specify method used)

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 7 – Aluminum1100 - Specimen #7 Resistivity Measurements

Ractual =
Specimen Length* =

* Need to measure (specify method used)

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 8 – Carbon Steel1008- Specimen #8 Resistivity Measurements

Ractual =
Specimen Length* =

* Need to measure (specify method used)

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 9 – Stainless Steel 304- Specimen #9 Resistivity Measurements

Ractual =
Specimen Length* =

* Need to measure (specify method used)

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 10 – STAINLESS STEEL 316- Specimen #10 Resistivity Measurements

Ractual =
Specimen Length =

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

Table 11 – Monel 400 (Thin)- Specimen #11 Resistivity Measurements

Ractual =
Specimen Length* =

* Need to measure (specify method used)

Specimen Diameter Measurements

Ø1 / Ø2 / Ø3 / Øavg

Specimen VI Measurements

Vs,Nominal
(Volt) / Vs,Actual
/ I / V / Rspecimen = V/I
1
2
3
4
5
6
7
8
9
10
Avg =

Observations/ Comments:

© Carlos Casillas, PE • Chabot College •ENGR-45_Lab_02_Sp12_Resistivity_CCasillas_120227 • Page 1

Data Reduction Calculations

Reduce the Measured Values to a Resistivity Values

  • Be sure that units are consistent and reported

Consult the Literature and Determine a “Handbook” value for 

  • List your reference in Tablebelow
  • TextBooks, Handbooks, technical Journals, and WebSites are Acceptable References
  • Calculated the % from the literature value as
  • % = 100x(calc – lit)/lit

Table 12 – Resistivity Calculations

No. / Specimen / Area / Length / Resistivity  / literature / 
1 / Copper
2 / Brass
3 / Monel 400 (Thick)
4 / 80-20 Nichrome (Long)
5 / 80-20 Nichrome (Short)
6 / Nichrome - Chromel C (Thin)
7 / Aluminum 1100
8 / Carbon Steel 1008 (Soft/Ox)
9 / Stainless Steel 304 (Soft)
10 / Stainless Steel 316L (Hard)
11 / Monel 400 (Thin)

Table 13 – Resistivity References

No. / Specimen / Reference
1 / Copper
2 / Brass
3 / Monel 400 (Thick)
4 / 80-20 Nichrome (Long)
5 / 80-20 Nichrome (Short)
6 / Nichrome - Chromel C (Thin)
7 / Aluminum 1100
8 / Carbon Steel 1008 (Soft/Ox)
9 / Stainless Steel 304 (Soft)
10 / Stainless Steel 316L (Hard)
11 / Monel 400 (Thin)

EXTRA CREDIT (25%)

For ALL of the specimens (not just Cu and Brass) plot the V-I characteristic, and determine the value of the specimen Resistance using LINEAR REGRESSION

  • An MSExcel spreadsheet template for calculating linear regressions may be found on the ENGR45 course WebPage.
  • MATLAB may also be used for the Linear Regression
  • The STUDENT is expected to properly INTERPRET the results of the statistical analysis in order to give PHYICAL MEANING to the mathematical result(s)

Assuming that the regressed value has greater statistical validity than the average value, calculate the % between the two.

Attach your plots to the report. The plots should include data on the linear regression

  • The Slope Value
  • The Intercept Value
  • The correlation coefficient (R2) Value

If your statistical analyses reveal a significant INTERCEPT on some of the specimens; please then comment on the possible physical sources of this quantity.

FURTHER elaborate regarding the difference in composition, heat treatment (soft vs hard tempered) and any other factors that may be responsible for your observations (AND anything else you may wish to point out about your results, such as potential, major SOURCES of error in the measurements, and state your reasons). Cite any additional literature references to back up your conclusions.

© Carlos Casillas, PE • Chabot College •ENGR-45_Lab_02_Sp12_Resistivity_CCasillas_120227 • Page 1