Experiment #2 Resistor Statistics

• The object of this experiment is to generate a histogram demonstrating how many resistors in a sample of the same nominal value meet specifications.

• A histogram is a plot that shows how many of an item fall into specific “bins”.

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Procedure

• Each student 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 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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Example Histogram

Histogram for 1000 Ohm Resistors

0

0.5

1

1.5

2

2.5

3

3.5

900 950 1000 1050 1100 More

Measured Value

Nu

mb

er

in R

an

ge

Frequency

R# Value

1 1000

2 1050

3 990

4 1075

5 950

6 899

7 1102

8 1080

9 1005

10 1020

Bin Frequency

900 1

950 1

1000 2

1050 3

1100 2

More 1

Raw Data Table Generated by Excel

Plot of Excel Table Data

Number of resistors with values < or = to 900

Number of resistors with values from 1051 through 1100

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TEAM #NAMES

NOMINAL VALUE

TOLERANCE

ALLOWABLE RANGE

MEASUREDVALUE

12345678910

AVERAGE

STD DEV

Data for Experiment #2

=

=

=4

Preparing to Plot a Histogram

• Before you start to generate a plot, create 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 the range was 400-800, I would generate the following sequence:

400500600700800

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Generating a Histogram Table

• Click on the “Data” pull-down menu• Select “Data Analysis”• Select “Histogram”• For Input Range

– Enter the cell range with your resistance measurements (e.g. a4:a20)

• For Bin Range– Enter the cell range of your 5 values

• For Output Range– Enter the cell that you want to be the upper

left corner of your histogram table6

Generating a Histogram Plot

• Select (click and drag the cursor over) the table that was created using the histogram command

• Click on the “Insert” pull down menu• Select “Column”• Select chart type• You’ll see a preview of your plot, click “next”• Enter a label for the x axis and change the plot

title from “frequency” to something with your nominal resistor value in it, click “next”

• Select “as object in sheet 2” in last step then click “finish”

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What needs to be turned in

• A printout of the data table including:

– The original data– The histogram table– The histogram plot

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