This introductory section is intended for you, the student, to use as a guide and reference for general physics laboratory. It is important that you read the practices and procedures as outlined in this introduction.

Note that the labs are intended to provide you with

  1. hands-on experience with the concepts we have been going over in class;
  2. practice in taking measurements (a very important part of being in science or engineering);
  3. and practice working in groups.
I.  Laboratory Experiment Format
The format of the experiments in the manual are as follows:
1. Title
2. Purpose
3. Apparatus
4. Procedure
5. Analysis
6. Questions
7. Theory

These sections should be somewhat self-explanatory from their headings. Pay particular attention to the theory section. It will be helpful to you during the actual performing of the experiment and also when you write your lab report. The theory section contains definitions of terms, nomenclature, necessary formulas, wiring diagrams, equipment illustrations, and expected graphical results. It supplements both the Procedure section and the Analysis section.  Everyone is expected to read the assigned experiment before coming to lab. The lab will run more smoothly and the whole lab experience should be more satisfying if you read the write-up ahead of time.

II. Laboratory Report Format

Each group must submit a lab report for each experiment performed. The following format is recommended and should be adhered to closely unless your instructor decides otherwise. Use 8 1/2" x 11" paper and do not write on the back of the sheets. Write legibly or (even better) type, and use proper grammar. Points will be taken off for misspelled words and incorrect grammar. A small portion of your grade may be based on your in-lab performance.

1. Cover Sheet:
Title of experiment, your name, date that experiment was performed, partner's names.  (First and last names. Get the spelling right!)

2. Abstract:
1-3 sentences. Write a concise statement of the principle result that is described in this report.   This should include what you were trying to measure (or do) and then whether your measurement (or tinkering) managed to agree with the expectations.

3. Theory:
1-2 paragraphs.  Summarize the basic physics of your experiment. Include equations and other principle things the reader would need to know in order to understand the experiment.  Keep it short!

4. Experimental procedure:
Describe briefly how you carried out the experiment. Do not include relatively trivial things like turning on a switch. On the other hand, you should include descriptions of how you determine things that are necessary to the anticipated results.  This should be very short as well.  Mention the particular pitfalls in data taking that you discovered and managed to maneuver around.  You may need to recreate a wiring diagram or draw the apparatus in order to refer to it later during discussion.

5. Sample Calculations:
Include a few of your calculations in this section, e.g. one of each type. Do not show each and every calculation.

6. Graphs:
Include title, labeled axes, smooth lines through experimental data points, and slope calculations. Each graph should convey a complete message and be fully understandable without referring to any other section in the report. Further graphing rules are listed in the Theory section of Experiment #1 and other graphical techniques are developed in Experiment #2 and #3.

7. Tabulated Results:
Title final experimental results, standard or accepted values, if they exist, and percent errors and/or percent differences.   This is a very important section of the lab!  It is here that it becomes clear whether your data agree with the accepted value(s) or are self-consistent.

Percent error is used when comparing a result to an accepted value.
% error = ((X - Xs)/Xs) x 100
where Xs = a standard or accepted value
X = an experimental value

Percent difference is used when comparing two results from different experimental methods. The average of the two measurement is probably closer to the actual value than either measurement. So, the average is used in the denominator.
% difference = ((X1- X2)/Xavg)x 100 %
where X1 = an experimental value
X2 = an experimental value obtained by another method
Xavg= (X1 + X2 )/2
        = the average value of X1 and X2

This section should be a concise, tabulated summary of your results.

Two examples are as follows:

1. Comparing to an accepted value: Percent error
-- Accepted value Experimental Result Percent Error
Acceleration Due to gravity 980 cm/sec^2 960 cm/sec^2 -2%
2. Comparing two measurements of the same quantity: Percent difference
-- Method #1 Method #2 Percent Difference
Initial Velocity of Projectile 21 ft/sec 19.7 ft/sec + 6.4%

As a rule of thumb, ±3% error is considered reasonable for experimental results. However, don't always expect to get accuracy this good. In some experiments an 80% error might be reasonable because of component tolerances. The nature of the experiment has a bearing on the expected accuracy.

8. Discussion/Conclusion:
This section should not be a rehash of your results. Discuss how your results demonstrates basic principles of physics. Conclude whether your data agree with the accepted value(s) or are self-consistent. Give reasons for errors, personal observations, suggestions, and any other comments you feel are pertinent.

9. Answers to Questions:
Answer all assigned questions with complete sentences. Answer them so that the instructor can tell what question you are answering.

10. Raw Data:
The original raw data that you take in lab.  This should be easy to follow, in tabular form.  Poor data recording skills lead to poor writeups.  If your raw data is illegible, the grade will suffer.

Last updated Jan 2, 2002
Scott Nutter