Some objectives of this course:
Much of this course will be devoted to studying electric and magnetic fields, electric circuits and electronic measurements. Because of the ease, speed and precision of electrical measurements, in modern physics labs nearly all physical quantities (even ones not inherently electrical - e.g. displacement, time, force, pressure, temperature) are converted to voltages or currents with devices called "sensors" or "transducers." These electrical quantities are then measured with electronic instruments or coupled through electronic interfaces to computers for rapid and efficient data acquisition. Many of your experiments will involve the use of computers for data acquisition and analysis.
Two texts are required for this course: Practical Physics by G.L. Squires and a reprint of some sections of Introduction to Modern Electronics by J.C. Sprott. There are also on the Reserve Shelf in the Physics Library several books that should be helpful.
The faculty member in charge of the course is Bascom Deaver, whose office is in Room 311C, phone number is 924-6574, and e-mail address is bsd@virginia.edu. You are welcome to consult with him at any time about the course. He will present the lectures each Friday, give some additional information at the beginning of each lab section, and be available for help and discussion at various times during your lab period.
There are two laboratory instructors, each of whom supervises two lab sections. They will give you some specific instructions relating to their individual sections and also information about how best to contact them outside of class periods. Your instructor will help you work out exactly what is required of you each week and is the person to see if you wish to modify a given experiment or otherwise alter procedure. It is important to discuss special arrangements with your instructor if you should miss a lab period. The instructors grade all of the reports for their own sections. At the end of each semester, letter grades are assigned to the numerical averages in such a way that the letter grade distribution is the same for the students of both instructors.
There are two parts to the course:
1. Each Friday at 2:00 p.m. in Room 216 there will be a 50-minute lecture covering topics pertaining to the following week's experiment and describing the apparatus and techniques you will be using. Here you will have an opportunity to learn about and discuss the physical principles involved and the context and importance of the particular experiments you will be doing.
2. Laboratory Period - There are four lab sections that meet from 2:00-6:00 p.m. Monday through Thursday. You should be enrolled in one of these sections and always attend the particular section in which you are enrolled.
The experimental work will be done by teams of two people. We encourage free exchange of ideas between partners and also generally throughout the lab. We expect you to share the work of taking data and creating a lab journal. Lab partners will be switched each week in order to eliminate correlations in grades between people.
Pre-lab Report
At the beginning of each lab period, instruction sheets for the following week's experiments will be handed out. Before your next lab, you should study these instructions and complete the pre-lab report that is due at the beginning of the next lab period. The contents of the pre-lab report will vary, but it will usually include answers to some questions about the objectives, concepts or techniques involved in the upcoming experiments. Some weeks it will include solutions to some problems. It is extremely useful to prepare a list of theoretical results that you will need for your experiments and a concise summary of the procedures you will be using. You should keep a copy of your pre-lab report to refer to when you write your report after completing the experiment.
Clearly, a primary purpose of the pre-lab report is to have you prepare for the experiments before you come to lab. In spite of the great time pressures and inclinations not to do so, you should be conscientious in preparing for the experiments. You will learn much more, you will be able to complete the experiments in the allotted time, and you will not waste your time and that of your partner.
Laboratory Journal and Report
An essential part of experimental science is a short but carefully written record of what was done in the laboratory together with data, data analysis, and carefully and rigorously drawn conclusions and interpretations of the results. This is what distinguishes scientific experimentation from just playing around in the laboratory. There will be two other distinct parts to your written output for this course in addition to your pre-lab report.
1. The Laboratory Journal (Unpledged)
The first part is a laboratory journal where you record every relevant thing you do in the lab as you do it. Your journal should consist of short statements about what you are doing, apparatus diagrams where appropriate, tables of data, calculations and graphs etc. In short, what you do while actually in the laboratory should be recorded in your journal, and there should be enough words so someone reading it can understand what you did. Every pertinent fact and procedure should be recorded in clipped but clear English. Your journal is a chronological record with data placed right in the text as the data are taken. You should record the raw data, the actual readings you take. Then in separate columns in the data table record any results of calculations, even simple ones like changing units. You should plot graphs as you proceed. Since you will probably create some of your data tables and your graphs with a computer, they will necessarily be on separate sheets, but they should be attached as part of your journal.
We emphasize the importance of understanding what you are doing at each step, and knowing, while you are in the lab, whether your data are correct and meaningful. This necessitates making your calculations and graphs as you go along in order to make sure you have recorded all relevant data, have not made errors in your readings of meters or use of equipment, and have no defective apparatus.
You should produce two copies of your journal, one for each partner. (There is a copy machine in the library on the third floor.) No additions or changes are to be made to the journal after you leave the laboratory. In some cases, the members of a team may wish to make individual journals. This is acceptable, and if it is done, the journals will be graded separately. Otherwise both members will receive the same grade in the journal. Neatness and legibility count!
Summary of Lab Journal
1. Your name, name of lab partner, date of lab.
2. Record of data, with enough explanation to enable you and the instructor to determine the experimental setup and to do the calculations. Detail should be sufficient that, together with your report, anyone can reproduce your results.
3. Description of any problems in procedure.
4. Estimated or calculated errors in measurements.
5. Calculations and graphs.
6. No changes or additions to journal after leaving the laboratory.
7. The journal is not pledged.
2. The Laboratory Report (Pledged)
The second part of a working physicist's written output is a series of formal reports on completed experiments. These are the published papers, in which the results of the experiment and the conclusions drawn are written in a more formal and logical way. The experiment is described in enough detail so that the scientific community can understand what was done, but many of the details in the journal are omitted. The raw data may be included, or only the results of a complicated data reduction calculation may be presented. Maybe only graphs of the data are included if this is sufficient to support the experimenter's conclusions. These reports are the scientist's communication with the world. Normally, nobody sees the journal except the experimenter.
We do not think it makes sense to ask you to produce a complete formal report at home, since you will be handing in your journal. Therefore the part of your report which you write independently at home should be thought of as a continuation of your journal. In this part you reflect on your experiment, do any data analysis beyond what was necessary in the lab, plot additional graphs for clarification, interpretation, or cosmetics if necessary; answer any questions in the lab notes, and draw what conclusions and theoretical interpretations you can from your experiment. Any additions or corrections to items in your journal are to be made in this part (but made only in the report). Attach this part to your journal copy and hand them both in on time. The name of your partner should appear with yours on the front cover. For maximum effectiveness this report should be done while the experiment is still fresh in your mind.
One characteristic of a good report is conciseness. We do not require repeating in the report anything which is in the handout or assigned readings, and your grade will not be enhanced by it. Neither is credit given for sheer length. However, credit is given for demonstrating your understanding of experimental techniques and accuracy of measurement, correct use of units of measurement, and intelligent analysis of your data, including error analysis. Neatness and legibility count!
In order to encourage you to write the report as soon as possible after doing the experiment, we require you to hand in the report and journal one week after finishing the experiment. If they are late, ten points will be deducted from your grade for each week they are late. Writing your report promptly is very important. Generally, late reports suffer double jeopardy - in addition to deduction of late points, they are usually of lower quality than those turned in promptly.
Since we expect the report to be the work of each individual, we ask you not to work on it with your lab partners or others, and to pledge it.
Summary of Report:
When writing any report it is important to have in mind the audience you are trying to address. Assume for this report that you are writing for a hypothetical classmate who has a substantial interest in what you did, why you did it, and what conclusions you can reach from your measurements.
1. Title page, containing title of experiment, your name, name of lab partner, date report is handed in.
2. Introduction: A very brief overview of the objectives and conceptual basis of the experiments.
3. Body of report. Organize this into sections corresponding to the handout. State what was measured and how, and what you were trying to accomplish. Include sample calculations of the results and tabulate or graph the results. Pay attention to your units! Think about the magnitudes of the results. Are they reasonable? How precise are the principal numerical results you obtained? Discuss the data, and explain its significance.
4. Write your conclusions. Are they consistent with the introduction? This section should be short.
5. Total amount of time to write report: 3-4 hours. Expected length of report: No more than 8 to 10 pages, including graphs and tables.
6. Write and sign the pledge on your report.
7. Note late penalty: ten points per week!
Grading Summary
Four items will be considered in determining your grade for the lab:
1. Attendance at Friday lectures and performance in lab 15%
2. Pre-lab report 20%
3. Lab Journal 25%
4. Lab Report 40%
Suggested Time Allocations
Study of instruction sheets and references, pre-lab report 2-3 hours
Friday lecture 1 hour
Lab period 4 hours
Lab report 3-4 hours