Lab Guide for Physics 143, Fall 1996

TA: Douglas Wick Office: Physics 048 Office Hours: Mon. 11:30-12:30 and Wed. 12:20-1:10 or TBA Phone: 660-2549 Email: DMW2@phy.duke.edu

Every word of this handout is vital. You need to read this.

1. Lab Notebooks

Required: You must bring a lab book, "Jones and Bartlet Laboratory Research Notebook" (100 pages, avaiable in the Bryan center bookstore for $12.95) to lab this afternoon.

In your future career as a physicist, you will need good lab notebook skills. Your lab notebook is a legally admissible document of the work you've done and when you did it. You can use a good lab book to prove you discovered something first, or to prove to your boss that you weren't just playing Star Wars. Your notebook should include a rough sketch of the arrangement of the equipment, most of the key equations, a thorough list of the apparatus, and the experimental procedure. This is all so that you can pick up your lab book after five years have gone by and understand what you were thinking way back in 1996. Naturally, all the data you take should be included, and left in even if you later decide it's no good. Any mistakes should be crossed out with a single line - they might not turn out to be mistakes. No white pages should ever be ripped out for any reason. (These lab books make a copy automatically onto yellow paper - no carbon paper required.)

What does that mean for this course? You are required to purchase a lab notebook and bring it to each session. Everything you do should go down in the book. That includes your a pre-lab writeup (see below), your procedure, apparatus, and calculations performed during the session. This doesn't have to be in essay form but legibility and clarity are essential. Jotted notes are not good enough! Remember, this is for you to look at 5 years from now. "Wt. Dr" may seem clear to you when you write it down, but I guarantee that you'll have no idea what it means six months from now. Also, if you decide to change your procedure half way through, that's fine! Just write down the change and what made you decide to make the change. An example of a good lab write-up is at the end of this handout.

How will we grade your lab books? If we don't feel like we could walk into the lab room and repeat your work exactly using only your notebook, then you'll get a "C" for that day's notebook. If it's complete but very hard to read, that will get a "B".

Will you spend all your time writing stuff down? Yes, at first it will seem that way. But careful note-taking is an essential part of all science. Soon it will become routine. Your lab notebook should be more like a comic book or a diary rather than a novel; don't bother making it a work of art, but do show the action and the results clearly.

2. Preparation and Lab Hours

The scheduled lab time is Wednesdays from 1:10 until 3:10. I can be counted on to stay as late as 3:45 most days, but no later. Another session will be arranged, probably late Thursday or Friday afternoon. I encourage you to switch to the alternate time even if you don't need to - if there are lots of people in the Wednesday slot, I might not be able to give you as much attention as I would like to. We will arrange the alternate time in lab today (Sept. 3). Anytime you are sick or need extra time to complete a lab, you must arrange the extra time in the lab with Mike Carey (carey@phy.duke.edu) who has the other key.

Two hours a week is not a lot of time. You will not be able to finish your projects in the time available unless you come to lab prepared and ready to get right to work. You have only two weeks to finish each experiment. Thus there will be "A" weeks where you begin a new experiment, and "B" weeks where you complete that experiment. At the beginning of each "A" period, I will be collecting the yellow page (carbonless copy) of your pre-lab write-up. You may not enter the lab without turning this in to me. The pre-lab write-up should contain:

1. The date, your name, your partner's name, and the experiment you are working on. 2. A brief (4-10 sentences) description of the principle or effect being tested or measured. 3. A description of the apparatus and how you will use it to take data.

Leave the rest of the page blank. You will continue taking notes at the beginning of the next page. An example of a pre-lab is at the end of this handout. At the beginning of "B" sessions, no pre-lab will be required. However, in order to get timely results, you should probably have some ideas already down in your notebook of what to do next. At the end of each day (both "A" weeks and "B" weeks), I will collect your yellow copies of that day's notes and keep them for reference.

This policy places the burden of preparation squarely on you, the student. Written materials describing the labs will be handed out to you next week (probably Sept. 10). You may look around the lab or ask other students about the experiments you will be doing in the future. I and Prof. Gauthier will be available during office hours to discuss labs.

3. Grading Policy

The lab component of this course will be 30 percent of your overall course grade. The lab grade will be further broken down as follows: 10% pre-labs, 30% notebooks, 50% reports, 10% subjective (basically, did you show up on time and ready to work). The reports will be due in my box in the department office (Room 107) at 9 AM exactly one week after the "B" period in which the lab was completed. Each day late or fraction thereof will cost a letter grade (10%). The lab component of the course will not be graded on the curve. It is perfectly possible that all of you will get an "A". Your classmates are your greatest asset during this course, just as your colleagues will be in your career in the sciences. You may work with your lab partner or other students in the preparatory research, but every student should write their own pre-labs, other lab notebook entries, and of course reports.

Reports will not be graded on results. Of course, if your apparatus did not perform, it would be nice to see in your report a good explanation of what you think caused the trouble. Prof. Gauthier and I have done each of these experiments recently. This only guarantees that they worked once; as you will learn, sometimes machines develop personalities. That's when experimental physics starts to get fun.

In your report (3 to 5 pages, typed, double spaced) should be:

1. An abstract - three to five sentences that give the significance of your results.

2. A discussion of the effect and what physical principle it demonstrates.

3. A summary of your results and how you got them (a brief reprisal of your procedure).

4. Error analysis - at the minimum you must discuss the questions in each lab's handout.

5. A conclusion discussing reasons for systematic error and statistical error, with suggestions on how to improve the experiment.

In writing this report, you should pretend that you have been asked to prove some new bizarre kind of physics that some wild-eyed genius has just invented. The acceptance or rejection of these heretical theories hinges on your experimental results, which you have rushed into publication to resolve the controversy. Don't be pompous, but do be precise.

4. Schedule

The first day of class (Sept. 3) you will receive a handout detailing lab zero, statistical analysis. No pre-lab is due but you must come to lab this afternoon. The write-up for part A of lab zero will be due the following Wednesday (Sept. 10) when you come to lab (or other day TBA). In one of these two sessions you will get a tour of the lab room and a brief description of the experiments. Part B of lab zero will be due on Sept. 17 (or TBA) at the beginning of the lab period. Also due at the beginning of lab that week will be the pre- lab write-up for your first "real" lab. There are seven experiments planned, and each of you will do five, but there is no particular order required. Those of you who performed the spectroscopy and/or E/M experiments last year may not repeat those experiments. A sign-up sheet will be posted in the lab room to avoid conflicts. You and your partner may sign up for any or all five labs at any time. All of the experiments work (or did once), but some will be easier to perform than others. You will be sharing the apparatus with your peers in the other session, so try to be neat, and don't freak out if someone's disconnected a few wires. (Good lab notebooks will allow you to put it back the way you had it!) A sample schedule is given below.

Sept. 4: Came to lab, got lab zero handout.

Sept. 11: Turned in lab zero part "A". Got a tour of the lab. Found a partner, picked the order, signed up for labs 1-5.

Sept. 18: ("A" week: pre-labs due.) Turned in lab zero part "B". Turned in a pre-lab for lab one (the Photoelectric Effect). Got the photoelectric effect to work; started taking data but ran out of time.

Sept. 25: ("B" week: nothing due.) Finished taking data. Watched Seiji and Sarah work on spectroscopy experiment for a while.

Oct. 2: ("A" week: pre-labs due, and report from experiment one due.) Turned in spectroscopy lab. Tried to make apparatus work.

Oct. 9: ("B" week) Etc.

Note that the final week of lab work will be the week of Nov. 20. All papers will be due in my box before you leave for Thanksgiving holiday. (This will move the due date for the last lab up one or two days for the alternate-session students.)

Prof. Gauthier and I have tried to make sure all the labs are of a reasonable length and in good working condition. The lab portion of this course will be a lot of work, but we hope it will be a rewarding learning experience for you. We encourage you to take advantage of our office hours if you have any difficulties or if you have any feedback for us during the semester.

Last Modified: 4-Sep-96