How to Report on an Experiment

[Instructor's note: What follows here as acceptable procedure is adapted from a protocol found at]

A laboratory report should communicate, as clearly and concisely as possible, the rationale for the experiment, what was done, what the results were and what the results mean. On the basis of a report on an experiment a reader should be able to repeat it and get similar results. The report should be as short and simple as possible to accomplish this end. It takes practice to learn how to write a technical report which does this well.

You are likely to be working with one or more colleagues as you do each activity. One of you should be selected as principal investigator (PI). It will be the responsibility of the PI to 1) coordinate the work of the group; 2) ensure that all parts of the activity have been completed; 3) work with team members to ensure that the report is ready on time and is worth passing in. One report will be filed per group and one grade will be given. Clearly, all members have a stake in making the report as complete as possible. It is my expectation that each student will take a turn as PI at least once each quarter.

Your report should include the following parts:

1. Identify the experiment by name and give the date performed, PI's name (first and underlined) and that of your lab partner(s)

2. Abstract . Give an extremely short ( a few sentences will be sufficient) description of the object of the experiment and a statement of your principal results.

3. Theory Start with the motivation (or reason) for the experiment. Follow this with the theory behind the experiment. Give a brief presentation, in your own words, of the essential ideas behind the experiment. Include only the most important formulas (explaining the meaning of any symbols used). Do not give any derivations unless they are original. The purpose is just to establish the context of the experiment and state, for reference, the relations you will be using in analyzing your data. (The proverbial interested reader should be able to look up details elsewhere on the basis of your outline.) One paragraph, in good English, should suffice.

4. Experiment Succinctly describe, in your own words, the apparatus used and the procedures followed to get your results. It is best to do this without reference to the lab directions. Relying on your own memory is more authentic and provides practice for your powers of observation. Tell what you did so that someone else could duplicate it from your description. This is an instructive exercise, for your benefit, in attending to and understanding facts in a scientific manner and to give you practice in describing them intelligibly. Think of your reader as an intelligent physics student who has not done the experiment. You should demonstrate clearly to your reader that you know and understand what you did and can articulate it simply. However, do not copy the detailed diagrams in the lab manuals directly, a rough sketch of the apparatus showing the relevant physical variables (e.i. x, y, [[theta]], etc.) is appropriate. Emphasize sketches of the equipment but three dimensional artist's sketches are inappropriate. Such a drawing should illustrate what you have to say.

5. Data Analysis Give one example of each calculation made; it should be clear that you understand what you are doing. You may do the other calculations separately and include only the final results. For your own benefit (and for the instructor's sanity): BE NEAT! Calculate errors and show any error formulas used; again, include one sample calculation. Clearly state the results you obtain. Data should be presented in an organized form, such as in tables, charts and graphs, and stated in correct SI units. Do not use the tables from your original data sheets for this purpose. All data is to be recopied and reformatted in the Data Analysis section of the write-up. Experimental data should be compared to theoretical predictions and calculations. Include the error analysis in your tables and with your final results.

6. Conclusion Summarize, in a paragraph or two, what you conclude from the results of your experiment and whether they are what you expected them to be. Compare the results with theoretical expectations and include percent error when appropriate. Don't use terms such as "fairly close" and "pretty good;" give explicit quantitative deviations from the expected result. Evaluate whether these deviations fall within your expected errors and state possible explanations for unusual deviations. Discuss and comment on the results and conclusions drawn, including the sources of the errors and the methods used for estimating them. Include brief answers to the specific questions asked in the lab instructions.

7. Remarks

Please critique the experiment as presented in the lab directions. Could the lab be done in a better way? Do you have some other or original method for obtaining the same results? Your suggestions are encouraged and are used to improve this lab activity.

8. Data Attach an initialed (by me) copy of the data which you took in the lab to the back of your lab write-up.

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Last edited 01/01/06