"CANDLE IN A BOX"

INTERACTIVE LAB EXERCISE

                                                                                        EXPERIMENT PROTOCOL



EXPERIMENT

Experimental Objectives:
 

A) To locate a heat source in a cardboard box using collection
     of temperature data throughout the box and analysis of data

B) To experiment with volume visualization of temperature data
     from probes in a cardboard box under various temperature
     conditions
 

Materials:

  • cardboard box (size: 24" x 18" x 18")
  • 8 digital temperature probes (Vernier Direct-Connect Temperature Probes)
  • A to D converters with power supplies and cables to connect to computers
  • computers and software (Data Logger and Noesys) to process and display data
  • awl or punch tool to put holes in cardboard box (for probe passage)
  • heat source (desk lamp with 60 watt light bulb) (do not use Tungsten bulbs - or candles - in spite of the title!)
  • for cold source: ice, ice packs, or dry ice, and insulated gloves to handle dry ice and heavy Pyrex glass dish(es) to contain dry ice
  • black marker pens
  • "grease" pens or "crayon" pens for marking glassware
  • white (& other color) label tape
  • rulers
  • tape (mailing tape or duct tape)
  • weights for bottom of box to prevent tipping

Protocol:
 

  Set Up Experiment and Collect Data

1) Position the cardboard box so that it will open at the top.

2) Record the dimensions of the cardboard box.

3) Punch holes in the box for placement of the probes. (see #6 below)

4) Record the positions/locations of the holes in the box.

5) Connect 2 probes to each of 4 A to D converters, each
    attached to a computer.  See Fig. a.
 

Fig. a. Cardboard box tilted on one side for photograph to show probes and lamp inside box with 2 probe connections to one A to D converter and to computer outside box. During experiment, box is oriented with flaps opening toward ceiling and with lamp base on bottom of box.

6) Insert probe tips into holes in the box far enough so there is a 12-inch distance between the tips
    of each probe and its nearest neighbor. This way the probe tips form a 1-foot cube. See Fig. b.


Fig. b. Cardboard box in experimental orientation showing probe positions with probe tips 12 inches apart (12" ruler on bottom of box).

7) Open the top of the box, if it is not already open.

8) Place your heat source, the lamp, into the box and record its location.  At this point briefly
    test the lamp to make certain that it works. Be able to turn the lamp on and off outside of
    the box by a switch or by plugging and unplugging the lamp. Make sure the lamp is switched
    on but unplugged before closing the box lid. Loosely tape the lid shut and allow the air
     temperature inside the box to equilibrate (estimated to take 5 minutes).

9) Power on the computers and the A to D converters. Open the DataLogger software. Follow
    separate instructions in Appendix A for using Data Logger software and recording temp
    probe data.  (note: You will set your computer to record temperatures for a 20-minute period.)

10) Start your computer-driven recording of the temperatures. Your starting point is 0 minutes.
    Your computer software (Data Logger) should be recording the temperature readings.The
    temperature readings between 0 minutes and the time that the heat source is turned on
    (1 minute here) are the "baseline" temperatures.

11) At exactly 1 minute (Minute 1), the lamp should be plugged in (which turns on the heat
    source inside the box).

12) The computers will continue recording the temperature for each probe at 2 minutes, 3
   minutes, 4 minutes, 5 minutes, and 6 minutes. The data recorded at the times:  Minute 2,
   Minute 3, Minute 4, Minute 5, and Minute 6 are the "experiment" temperature readings.
    In regard to the computer-driven recordings, the frequency of data collection (temperature
    values over time) and the duration of data collection (how long data values are collected)
    are options that you set using the computer software itself.

13) After exactly 5 minutes of heat (Minute 6), the lamp should be unplugged (which turns off
    the heat source inside the box).

14) Continue recording the temperatures for 15 additional minutes (Minutes 6 through
    20). The computer should stop at 20 minutes if programmed correctly.
 

(Note: You can preset the amount of time the experiment will be recorded by Data Logger software.  We ran the experiment for a total of 28 minutes, that is, for 22 minutes after the heat source had been  turned off to collect the dataset we use here.)
 

15) Stop the computer recording of temperatures at the end of 20 minutes by clicking the Stop
    button at the lower left corner of the screen if the computer does not stop recording
     automatically.

Remember to save your computer-recorded temperature data file. You will have to use it later.

This Protocol continues in the Data Processing and Data Analyzing sections (See below.)
 
 

  Process Data I: 2D Graphs
 

                   16) Enter recorded data into a spreadsheet (like MS Excel) by cutting and pasting the data from
                        Data Logger in Tables under View.   See Fig. c.
 
 

            Fig. c. Part of Data Logger table displaying data associated with graph shown beneath.
 

                    17) Use Excel or another spreadsheet software to create 2-dimensional and graphs of the recorded
                         data. A typical and informative kind of graph would display temperature of the probes plotted
                         against time.  See Fig. d.

Fig. d. Temperature data from eight probes plotted against time. Graph created in MS Excel in same database file in which data are stored.

                    18) Analyze the results by examining the 2D graphs.

          19) Compare numerical data with graph(s) to gain insights about phenomena that may have
                occurred during the experiment.

  Analyze Data I: Mathematical Analysis:

          20) Process the numerical data mathematically by calculating differences between consecutive
               temperature values to reveal changes in rates of increase or decrease in temperatures.
               These are called "first difference" values. Graph the newly calculated "first difference"
               values against the experimental time increments. This new graph should give additional
               insights about the experiment results. For simplicity in this analysis we have used data
               from only two probes, Probes 3 & 4, graphed first as temperature over time. See Fig. e.
               Then we created a "first difference" graph using values from Probes 3 and 4.  See Fig. f.

Fig. e. Temperature data from two probes, 3 & 4, plotted against time.
 
 

  Fig. f. "First difference" values based on differences in temperature data

                                                       from two probes, 3 & 4, plotted against time.
 
 

         21) Repeat the calculations of differences using the "first difference" values created in number
              20 and graph the newly-calculated "second difference" values for additional information
              about the results.  See Fig. g.

    Fig. g. "Second difference" values based on differences in "first difference" values
    for Probes 3 & 4 plotted against time.

          22) Analyze results again by comparing the three different 2D graphs.
 

  Process Data II:3D Graphs (Volume Visualization)
 

         23) Create a series of 3-D graphs of temperature data points from the probes inside the
              cardboard box using Noesys (volume-rendering computer software). (Follow separate
              instructions for using Noesys software in Appendix A.) Use Noesys to process data
              and render (draw) a 3-D computer graph/image from the data.  See Fig. f below.

                        Fig. f.   A 3-dimensional interpolated image created from temperature
                        probe data using Noesys software. The upper right corner (data from
                        Probe 3) indicates highest temperature, while the lower left corner (back
                        corner, data from Probe 8) indicates lowest temperature.

Analyze Data II:
 
 

        24) Analyze results again by comparing the different 3D graphs/images with each other and
             with the graphs and the numerical data.
 

        25) Try to determine:
           a) where the hotter air temperatures in the box are located,
           b) how the hottest and coolest areas in the box change over time, and
           c) where the actual heat source is located in the box (or cold spot if ice or dry ice
                   is used).
 

        26) See Homework Sheet (below) for more advanced techniques using temperature
             probe data over time to create additional T3D images with Noesys.
 
 

Advanced Mathematical Analysis: (see special "Cooper's Corner" on Interpolation Exercise)
 
 

        27) Fill in Lab Worksheets, complete Homework Sheet, and answer Questions below.
 
 
 
 

  Lab Worksheets:
 

     Attach data table printouts from Data Logger here or fill in tables below.

     1) Temperature Data:

      a) "Baseline" Temperatures:
 
 

Temperature oC

Probe No.

Location

 

    b) "Experiment" Temperatures (for just one point in time):
 

Temperature oC

Probe No.

Location

      2) Data Volume Visualization Printouts, with Orientation Labels on Each:

Hand in two printouts of the 3D graphs/images (volume visualization printouts) you have created
from the "experiment" temperatures, one uninterpolated 3D image and one interpolated 3D image.
Please write the filenames (both Database File Name and View File Name) used to create the images on
each of the printouts.

    3) Data Files/Folders and Saved Image Files - Data Structure & Location:

Use the worksheet below to record the filenames and computer pathways of those files to enable you or
your instructor to locate your files on your computer at a later date.

File/Folder Name                Location on Computer                         Computer #

 

  Homework Assignment Sheet:

(note: For number 1 on this homework sheet we assume that the student has after class/lab access to
computers with all the same software needed to conduct the experiment and analyses during lab time.)


    1) Produce a 3D Image / Visualization of Temperature Differences

a) Produce a volume visualization (3D image using T3D) of the temperature differences between the
    baseline temperatures and the experiment temperatures for every minute (or every other minute if the
    experiment was 20 to 30 minutes long). In other words, you will need to work with the values from
    Minute 0 and Minute 1 (the baseline temperatures), values from Minutes 2 through 6 (the
   experiment temperatures), and values from additional time during the return to equilibrium.

b) This is more involved than it might seem, as you must discover how to set up the database in the Noesys
    software. (Explanatory Note: Apparently only databases with three dimensions can be used to create
    3D images in T3D. Even though you will be able to set up dimensional databases, T3D apparently does not
    recognize or open those files, so you will not be able to create images from them. If you wish to create an
    image showing temperature changes over time, you will be able to use only the probes in one plane plotted
    against time. This will produce a 3D image.)
 

c) How much did the temperature vary after the heat source was turned off? (This refers to Minute 6 and
    temperature data after Minute 6 in this protocol.)

d) If the temperature did not return to the original baseline temperature, or lower, in your experiment, how
    long would it take for the temperature to return to baseline temperature? The process you use to determine
    this is called extrapolation. You will try to estimate, or if possible, calculate, an unknown value or value
    set from known values.

e) An important process used in the Noesys/T3D is interpolation, in which there is production of an image
    showing gradients between values (or perimeter points in this experiment). What is the definition of
   interpolation? How does interpolation differ from extrapolation?

    2) Produce a Brief Report.

    Hand in a brief report on what worked, what did not work, your recommendations for improvements or
    changes in the experimental design, and your conclusions from the data processing and data analyses.

   OR

    3) Produce a Standard Lab Report.

    Using instructorís direction, produce a more complete, detailed lab report including: experiment
   objective, materials, methods, data, results from data processing, 2D graphs, 3D graphs/
   images, discussion, conclusions, and suggestions for experiment variations or for a new
   experiment. (Web site on how to write lab report:
http://www.bio.davidson.edu/Biology/Courses/Bio111LabMan/Preface%20C.html )

  Questions:
 

1) Which probes showed maximum temperatures over time? Where were they located in the box?
 

2) Based on differences in probe temperatures over time, what can you deduce about changes in air temperature
    in the box? What can you deduce about the location of the heat source in the box? Do you have any direct
    evidence that pinpoints the location of the heat source in the box? Or did you have to estimate the location of
    the heat source?
 

3) Was the heat source turned on during the entire experiment? How could you determine this from recorded
    data and graphs/visualizations?
 

4) Did the location of the hot spot(s) in the box change during the experiment? Explain changes over time that
    you detected.
 

5) Which were most helpful in answering these questions: numerical data, 2D graphs, 3D graphs/images,
   or other? Explain.
 
 

  Acknowledgments:

We gratefully acknowledge the help of the students in the Fall 1998 section of the Biological Imaging and Visualization course at Trinity University, our very capable student assistants Julie Stephens and Erica Gutierrez, our web consultant Seven Bohannon, and Physics professors Dr. Fred Loxsom and Dr. Richard Bartels.

The authors' efforts are being funded through an NSF CCD grant (95-54805) where synergistic relations between statistics and biology education are being sought.


  Literature References:
 

Coleman, G.J., & Dewar, D. (1977). The Addison-Wesley Science Handbook. Don Mills, Ontario:
    Addison-Wesley Pub.

Graham, I.S. (1997). HTML Stylesheet Sourcebook. New York: John Wiley & Sons, Inc.

Greenberg, L.H. (1975, 2nd ed.). Discoveries in Physics for Scientists and Engineers. Philadelphia:
    W.B. Saunders, Co.

Tobias, S. (1992). Revitalizing Undergraduate Science: Why Some Things Work and Most Donít.
    Tucson, Arizona: Research Corporation.

Williams, J.E., Metcalfe, H.C., Trinklein, F.E., Lefler, R.W. (1968). Laboratory Experiments in
    Physics. New York: Holt, Rinehart & Winston, Inc.

Trinity University Biology 1119 Laboratory Manual for Organismal Structure and Function, 1998,
    eds.: R.V. Blystone and D.T. Villarreal

(software) Data Logger (Macintosh Version) vers. 4.5. (1990-1994). Tufts University, distributed by
    Vernier Software, Portland, OR.

(software) Noesys Suite, T3D, Plot and Transform (1997). Sterling, VA: Fortner Software

 

 

Last Update: 12 May,1999