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EGR 101Resistance Lab Handout
Read this before class on TuesdayBring it to class with you
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Reminder about TeamingShare the technical loadMake sure each
team member understands whats going on
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Digital Multimeter (DMM)Used to measure the following:Voltage DC
and ACCurrent DC and ACResistanceCapacitanceTemperature w/ extra
probe
Also used to check:DiodesTransistors
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Today Well Use the DMM to Measure ResistanceResistors restrict
the flow of current, given a fixed voltageUnit = Ohms, They come in
different packages
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Color CodeThe resistors well test today have a color code to
identify their resistance and tolerance.
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Band 1 (closest to the end) first digitBand 2 second digitBand 3
power of ten multiplier (most cases simply the number of zeros)Band
4 tolerance (Red = 2%, Gold = 5%, Silver = 10%, none = 20%)Resistor
Color Band Code
ColorValueColorValueBlackBrownRedOrangeYellow01234GreenBlueVioletGrayWhite56789
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What is Tolerance about?If a resistor has a nominal value of
1000 and a tolerance of 10 % then individual resistors with the
same nominal value are allowed to vary in their actual values from
900 to 1100 and still be considered acceptable.Any resistor
fabricated with an actual value outside that range should be
rejected as not meeting specifications.
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Ultimate Goal of this LabTo generate a histogram demonstrating
how many of your resistors meet specifications.A histogram is a
plot that shows how many of an item fall into specific bins.
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Example HistogramRaw DataTable Generated by ExcelPlot of Excel
Table DataNumber of resistors with values < or = to 900Number of
resistors with values from 1051 through 1100
R#Value110002105039904107559506899711028108091005101020
BinFrequency90019501100021050311002More1
Chart1
1
1
2
3
2
1
Frequency
Measured Value
Number in Range
Histogram for 1000 Ohm Resistors
Sheet1
R#ValueBinFrequency
110009001
210509501
399010002
4107510503
595011002
6899More1
71102
81080
91005
101020
900
950
1000
1050
1100
Sheet1
Frequency
Measured Value
Number in Range
Histogram for 1000 Ohm Resistors
Sheet2
Sheet3
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Practice ProblemsBrown Blue Red = Yellow Violet Gold = 33 k Ohms
= 1.8 Ohms =
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Resistance Lab Part 1 (45 minutes)Each team will be given a
package of resistors.For each resistor,Determine the expected value
of resistance by applying the color code.Measure the actual value
of the resistance by using the ohmmeter function on the Digital
Multimeter.Compare the actual and expected values of resistance
does the actual value fall within the allowable range?Enter your
results in an EXCEL table, as shown on the next page.
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Data for Resistance Lab Part 1Names:Team #Determined from color
band codeLeader:Timekeeper:Recorder:Eg: 450-510
Ohms100*(Meas-Nom)/Nom
Sheet1
ITEM #NOMINALTOLERANCEALLOWABLEMEASUREDVARIATION
VALUERANGEVALUE(in %)
1
2
3
4
5
6
7
8
9
10
&C&"Arial,Bold"&11EGR 108SPRING 2006
RESISTOR VALUES -- PART 1
Sheet2
Sheet3
400
500
600
700
800
MBD000B249D.xls
Sheet1
ITEM #NOMINALTOLERANCEALLOWABLEMEASUREDWITHIN
VALUERANGEVALUETOLERANCE?
1
2
3
4
5
6
7
8
9
10
&C&"Arial,Bold"&11EGR 108SPRING 2006
RESISTOR VALUES
Sheet2
Sheet3
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Resistance Lab Part 2 (55 minutes)Each team will be given a
sample of resistors having the same nominal value.For each
resistor: Determine the nominal value from the color code.Measure
and record the resistance of each resistor in the sample.Enter your
data in an Excel table (sheet 2) as shown on the next page. Plot a
histogram bar graph of the measured values and determine the mean
and the standard deviation of the resistance values.
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Data for Resistance Lab Part 2
=
==Leader:Timekeeper:Recorder:
Sheet1
TEAM #
NAMES
NOMINAL VALUE
TOLERANCE
ALLOWABLE RANGE
MEASURED
VALUE
1
2
3
4
5
6
7
8
9
10
AVERAGE
STD DEV
&C&"Arial,Bold"&11EGR 108SPRING 2006
RESISTOR VALUES -- PART 2
Sheet2
Sheet3
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Preparing to Plot a HistogramBefore you start to generate a
plot, generate a sequence of 5 numbers in your Excel sheet, equally
spaced, from the minimum of your allowable range to the maximum of
your allowable range.For example, if my range was 400-800, I would
generate the following sequence:400500600700800
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Generating a Histogram TableClick on the Tools pull-down
menuSelect Data Analysis(If you dont see Data Analysis, click
Mcrosoft logo, click excel options at the bottom, select Add-Ins
and then select Analysis ToolPak)Select HistogramFor Input
RangeEnter the cell range with your resistance measurements (e.g.
a4:a20)For Bin RangeEnter the cell range of your 5 valuesFor Output
RangeEnter the cell that you want to be the upper left corner of
your histogram table
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Generating a Histogram PlotSelect (click and drag the cursor
over) the table that was created using the histogram commandClick
on the Insert pull down menuSelect ChartSelect Column chart type
(default), click nextYoull see a preview of your plot, click
nextEnter a label for the x axis and change the plot title from
frequency to something with your nominal resistor value in it,
click nextSelect as object in sheet 2 in last step then click
finish
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What needs to be turned in:Everyone's practice problemsA
printout of the data table from the 1st experimentA printout of the
data table from the 2nd experiment including:The original dataThe
histogram tableThe histogram plotEach participating team member
needs to print and sign his/her name
*****Explain Allowable range, mean and standard deviation
