Each homework problem is an example of a "brief technical note". You have a specific piece of technical information to communicate to a fairly specialized audience. You need to explain carefully, so that your hard work in understanding the problem is transmitted.
 Outline
 Write to learn. Whether you've worked through a problem quickly, or it's taken you ages, the process of writing it clearly will help you clarify your thoughts, recall what was extraneous, and find the central pieces of insight.
 Have a target audience in mind. For most classes, the target audience is a student at the entry point of the present class. Remember how you felt when you started learning the material, and supply the same guidance that you and your peers needed when you began. The target audience is never the instructor.
 State the problem briefly. This doesn't mean rewrite the question, but it is helpful to give a onesentence statement of the goal. For example: "The terminal velocity of a mass m falling through syrup is found by ..." is a much better opening sentence than "v = ..."
 Have you provided a large, clear, beautifully labeled diagram? There are few problems in physics that do not benefit from a diagram.
 Have you explained the important points in words? Equations & symbols are the physicist's shorthand notation, but symbols must be defined, and treat equations as sentences. Have you defined vectors, constants, etc., so that your notation is clear? A long proof requires prose to explain the reasoning.
 Have you provided enough steps so that one of your peers could follow the logic? Here is where you have to develop judgment. It is not sensible to write every step (canceling a factor of 2 is trivial), but you cannot expect your peers to follow if you do not provide adequate intermediate steps.
 Have you drawn a clear conclusion, supported by watertight reasoning?
 Have you highlighted the physics  symmetries, large and small limits, connection to other common problems, etc.?
 General appearance:
 Is your penmanship such that your work is clearly legible and free of smudges? Space equations, particularly those with fractions, at least a line apart to ensure legibility. Make space for your work  don't scrunch afterthoughts into the end of the line.
 Are your diagrams and tables large, clear, and adequately labeled? Do symbols used in graphs and diagrams correspond to those in your prose?
 Do graph axes have labels (and units if applicable)? Have you chosen ranges for maximal information transfer?
 Have you checked spelling, grammar, and syntax? Remember that equations are sentences, too, and they should be part of the syntactical flow.
 Creativity:
 Is your work original? Never plagiarize the work of others nor allow others to copy yours. Controlled collaboration on technical aspects is encouraged (see section on collaboration in "General Information/Ground Rules", but your writing and synthesis should be entirely independent. Acknowledge contributions to your work from others.
 Choose words for clarity and precision. Avoid long, rambling sentences and strive for crisp, clear prose.
You are allowed to be funny, but never disrespectful, profane, or arrogant.
 Things to consider:
 Don't be verbose. Many students, faced with the injunction to "use words", produce something like this:
"Newton's law, which says that the force is equal to the mass times the acceleration .." which conveys no more information than
"F = ma, where F is the force applied to a mass m producing acceleration a." The second version introduces symbols for later use, and it is crisper and clearer. Equations are succinct and convey information to a scientist much more quickly. Incorporate equations properly into the flow of the text.
 It doesn't always have to be long! A few choice words make all the difference.
 Use your discretion. There is no single way to lead a reader through your work. Ask yourself whether you would be satisfied to read your work if it were presented as course notes provided by an instructor, or in a text book.
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Most of the guidelines for writing homework also apply to lab reports. Target audience, clarity of thought, precise definition of terms, presentation of arguments, clear illustrations, good layout, good grammar and spelling are all important.
 Outline
Lab reports most closely mimic the research paper, which follows a fairly standard form in most disciplines (including humanities):
 An abstract summarizes the results and major findings of the experiment.
 An introduction/motivation puts your work in context. In your lab report, it will likely set up the model you intend to use to understand the physical system, which provides a motivation for the exploration, but in more advanced work, it might also survey the literature in the field.
 The methods section describes the experimental setup (or the computational or theoretical methods).
 The results section describes the outcome of your work.
 The analysis and discussion section interprets your work for the reader (how well have you modeled the system?) and brings your own insight to bear. Sometimes, the analysis may be better incorporated with the methods, and sometimes the analysis and discussion are presented as two separate sections. This depends on the exact nature of your project.
 The conclusion summarizes, and looks forward.
There is onlyt lab write up in PH424 and no template is supplied, but you can refer to your PH421 template for general guidelines. Think carefully about how you would like information presented to you if you were required to repeat this laboratory exercise and interpret its results if you were a newcomer to this class. Think about structure, about organization, and about honest reporting and interpretation.
 Describing accuracy and error:
One important aspect of an experimental lab is that different from other types of assignments is that experiments have finite accuracy and/or precision, and so the question of what students often call "error analysis" arises. I don't like this term particularly because students often use it to shrug off differences between what they think the teacher wants them to measure and what they actually did. I prefer to think of modeling a system, and finding whether the model is a reasonable representation of the system, and whether the experimental set up is capable of distinguishing competing models. There are certainly welldefined quantitative ways to do this, but, to be honest, we do not pursue them very hard in this course. But we take a commonsense approach that is a good starting point for more quantitative analyses.
 You must be very clear how accurately you can measure something. This means that significant figures are very important. For example, if you quote a PH211 lab measurement of gravitational acceleration as g = 9.877658 m/s, the scientist's response is, "With that equipment? I don't think so!" The number of figures carries an implicit statement about the accuacy of your measurement. Be very careful, particularly when you present numbers in a spreadsheet, that you quote the right number of signicifcant figures.
 Don't ever ascribe discrepancies between results and expected outcomes to "human error". This is a completely meaningless term. If the human made a mistake in a measurement, the human must fix it.
 Do make reasonable estimates of error and repeatability. If you measure an interval on an oscilloscope, note the smallest division  you probably can't measure to better than 1/2 of one of those. If you make a judgment about where a maximum is, then do it a few times and see how repeatable your measurements are, and compare with those of a peer. Is the signal stable?
 Do make use of your knowledge of statistics to find the mean, the error in the mean, and do simple regression analysis.
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