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Handout on Lab Reports

This is a skeleton outline of what I expect from you in your lab write-ups. It should be taken as the bare minimum required, and should NOT be used as a checklist. My philosophy is that you all know what a good lab report should look like, so there will be some things you should do that are not covered here. At this point, I should not have to remind you that I expect these to be written well, that every graph should have labelled axes, and that they should, if possible, be typed. Most importantly, use your head! If you think something is missing, put it in there. Likewise, if something is painfully obvious to a child of three, don't write about it! I grade on content, not looks.

Okay, so enough of the heavy-handed scare paragraph, and on to how these should look. Try to write them as you would a journal article (though you should be able to do a better job than some of these bums getting published today). Today, scientific journals seem to follow a fairly set format, with the paper being divided into introduction, theory, apparatus & procedures, results, and conclusions & discussion. While it may seem hokey to write up an intro lab this way, doing so does provide an opportunity to write a paper in an environment where your scholarly reputation is not at stake--so take this chance and practice!

Introduction This is likely to be the hokey-est part. You will either have to pretend that you're a researcher in the 1800's doing all this for the first time or you'll have to pretend that someone in the 20th century wanted you to go back and verify that cathode ray tubes really do work the way they are supposed to. This should be a very general paragraph, designed to get the person reading your article interested in (if possible) and aware of what you are doing and, more importantly, WHY you are doing it. You should therefore answer questions like: What was the experiment? Why did we do the experiment? What is its importance? What was it designed to show? The goal is to place the experiment in a broader context, so your reader knows what you are talking about, and why you did what you did. If you do this well, the reader will remain interested long enough to finish reading the paper. It's a sales pitch.

Theory This section should contain all theoretical calculations necessary to predict the outcome of the experiment. You should derive every equation from basic principles, so don't just list something as "eq. 24-5 from the book"--instead, start with basics like Coulomb's law or the definition of an Electric field, and do the derivation yourself. Every derivation should be explicated, so they should not look like a rushed exam solution. Instead, they should look like the examples in the book or like Cassola's quiz solutions. Make them clear enough so that any student in your class could understand them, and be sure to note any approximations and assumptions you make. This will usually be a natural place to put the answers to questions in the lab manual, though some may be more natural in the discussion and conclusions section. Regardless, you should answer all questions in the lab manual somewhere in your write up.

Apparatus & Procedure Here you should describe the apparatus you used, including drawings, circuit diagrams, and any tables you think would be helpful in understanding exactly how you set up the experiment. You should also define any terms you use (e.g. explain "battery 1" is the 1.56 volt battery). You should also give a detailed account of how you got the data, and any problems you had. So, for example, a table of batteries and their voltages would be appropriate, possibly including a few entries on combinations of batteries used to get higher voltages (or just a brief comment). This is also the time to discuss what worked and what didn't, so you might include a comment like, "battery 2 started off at 1.45 volts and dropped to 1.30 by the end of the period, so I don't trust the battery 2 results". Basically, you want to write this section so that I could walk up to your lab station and duplicate exactly what you did using only your write-up.

Results Analyze your data (if necessary) and decide how you are going to present it. Sometimes graphs are good, but tables may be all you need. Compare the data with theory, and explain any difference between the two. Take into account that every experiment is subject to some reasonable experimental error, so if you don't get what you would predict, and you're sure you did the calculations correctly, explain why you got what you did. So, if your electron beam kept jittering about, you might explain, "we believe that a significant source of error was introduced when the members of a rival group produced a small electric cattle prod, which they used mercilessly to..." Well, you get the picture.

Conclusions This is essentially an extension of the results section, but here you try to put your results in a broader context. It is here that you should state whether or not you think the experiment agrees with theory, and discuss what you might do to make the experiment better. Since you are writing this as a journal article, pretend that you have a hefty grant, so you could buy a bigger CRT or a better power supply if you needed one. Finally, you should wrap up by once again moving to a slightly broader picture. I leave it up to you to find a nice way to wrap up the lab. Note that things like suggestions for further research and possible or current applications of the phenomena you studied are natural candidates for doing this.

I expect that these lab reports will be well-written. Technical writing is difficult, but not impossible, and is extremely important in the real world. These reports should come to about 5 pages, double spaced, which includes graphs and tables. If they come to less than this, but you believe that you have covered the subject adequately, fine. That's considerably better than padding the page count with a bunch of garbage!

Finally, I don't mind if you make copies of diagrams or sketches in the book or the lab manual, since this isn't an art class. However, the derivations, graphs, and words should all be your own. Anyone crossing this line runs the risk of being subjected to the University's plagiarism policy. Ever read it? It's nasty. Don't make me use it.

Look at my thoughts on the critique.

Look at the instructions I handed out on the day of the critique.

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