Dr. Wragg's Physics Labs

Guidelines for Lab Reports

General
A lab experience is an integral part of your exploration of the concepts of the physical universe. The laboratory is a hands-on, active environment. Working in teams, you will carry out experiments which will allow you to apply, verify, or discover concepts, principles, and laws. Some investigations will be cook-book in form; i.e., the procedure will be set out step-by-step. In some activities, you will be the scientist; i.e., you will have to design all of the steps for a procedure which will allow you to answer a question. All experiments require observation, measurement, analysis, drawing conclusions, and presenting your results.

If you have a question, comment, or complaint please let me know. Even an anonymous note under my door is fine. Note that there is an anonymous web-based email page available from my home page and is linked from the top of this page. Don't let my published office hours be an impediment to finding me at any time you have a question. Ordinarily I am pleased to see you any time you can drop in. You can phone or email ahead of time to set up a meeting if you wish. I am usually around. Please leave me a note if you can't find me.

The Department of Physics and Astronomy has adopted the following goals and objectives for its introductory physics labs:

Goals

Objectives

General Structure
We have 3 hours for each lab exercise. During the first lab period you will be assigned to a group. The group will be changed from time to time during the semester. You should exchange phone numbers and e-mail addresses with your partners. All members are expected to participate in the lab process. At the conclusion of the lab period all equipment will be restored to its original order. Note that lab is not a race to see who can finish first.

Generally lab reports will be be a collective effort submitted by the entire group. At any time a student may choose to prepare and turn in an individual lab report, independent of their lab partners. Lab reports will be due either at the end of the laboratory period or at the beginning of the next class meeting. I will specify which is the case early in each lab period.

Attendance
Attendance is important. You are only allowed to miss one lab for any reason. I drop the lowest lab grade, and if you miss a lab early in the semester, then are sick later and miss another, you are out of luck. One of the grades of "0" will get dropped, but not the second one.

Tardiness is rude, especially to your lab partners. It disrupts the flow of the class. Please be polite to your classmates and me by being on time. I will penalize students for tardiness. One built-in penalty is the possibility of missing a quiz, or not having much time to do it. Tardiness and absences will also be considered when assigning grades. Serious offenders will be penalized.

Lab Report
The standards for the lab reports will go up as the semester progresses, as you are learning how to observe and communicate effectively. Please take heed of my comments to ensure the highest possible grade for you and your lab partners.

Due Dates
Late reports may be accepted (at my whim) but are usually penalized by at least 20%. Some (perhaps even many) lab reports will be due the day of the lab, by the end of the lab period. Others may be due the beginning of the following week's lab period.

Quizzes
Quizzes may be given at the beginning of lab. They will be about anything you can reasonably be expected to know. This usually means they will be relevant to the previous lab. There will be no make ups for missed quizzes. As with the labs themselves, I omit the one lowest score. All others count, regardless of the reason for missing.

Grades
I don't give you an advance guarantee of points resulting in a specific grade, although I will give you fairly specific feedback any time you request. I consider 8/10 on a lab to be "B" work and 6/10 on a lab to be "C" work. I encourage you to see me at any time for my assessment of your work. I will drop your lowest lab and grade and your lowest quiz grade. Do not spend your one dropped grade lightly. The grading distribution is as follows:

   Quizzes      15%
   Lab Reports   85%
   Total        100% of course grade

Guidelines for the Lab Report

Ordinarily, reports due the same lab period will not be typed, those due the next week will be typed. The Physics department and the college maintain computers for your use. In either case please make sure that the names of all people participating in writing the report for your group are on the lab report.

Format of the Report
There is no single template for every experiment. There is more than one way to effectively structure a report. They tend to share common features: what you did, why you did it, what you got, and what it means. A well thought out and well written laboratory report not only serves to condense your experiment into an easily remembered form but also frequently provides additional insight as you deal with questions arising in summarizing your experiences.

Lab reports commonly have sections such as introduction, procedure, data, results, and discussion. Discussion of the limitations of the experiment, and intrinsic sources of error are almost always appropriate. Note that mistakes on the part of the experimenter are NOT considered intrinsic sources of error.

Most importantly, a good lab report will show to the reader that you clearly see the physical principles involved as well as how this experiment employs that principle. In our laboratory exercises accuracy is slightly secondary to the principles involved. However, a "10" report must show care and accuracy in the measurements and the computations, as well as insight into the experiment.

A good lab report is: neat, clear, well organized, complete, thoughtful, and reflects your understanding of the laboratory. Graphs should be on graph paper or computer generated plots. They should be a suitable size. It is difficult to make a graph too big and easy to make it too small. Generally, a graph worth doing is worth at least a half-page of space. Put the objective and procedure in your own words, but don't make them too extensive. Sketches of the apparatus, with important features and variables labeled and measurements shown are almost always a necessary ingredient in a good lab report. The sketch is particularly useful in connecting variables in equations with physical aspects of the apparatus. Don't abuse significant figures. The aforementioned features are required for a grade of 8 on the report. To get a 10 a lab report has to demonstrate all of the above, and show special insight in the performance and/or interpretation of the lab.

Intro Physics Lab Report Tips

• Communicate: Most of what makes a good physics lab report has very little to do with physics. You are working on general observation and communication skills, and the ability to draw valid conclusions. These skills are valuable in any field. Make it clear and concise.
• Objective: This is the experimental objective, not the pedagogical one.
• Procedure: Keep it a very brief narrative or a series of steps. Don't refer to the lab manual.
• Errors: Quantify the errors intrinsic to the procedure and tools. Looking at these errors allows the reader to have a sense of the quality of your results. Have some sense, or explicit statements about how big an effect the uncertainties and errors had on the result. Human error (i.e., a screw-up) is not what goes here. If you make a mistake, then fix it.
• Tables: Data and results can often go in the same table. Put units in the column header.
• Trials: How many trials do you need to do? As in a real job, you have to ask the questions, "how long do I have to do the experiment, how long does a trial take, how much money does each trial cost, how consistent are the results of each trial?"
• Diagrams: Make them simple, schematic figures, not artistic. Usually diagrams show variables that are used in equations. That is, in addition to showing the physical set-up, they connect the physical reality to the mathematical abstractions.
• Results and Discussion: This is where you give your answers, discuss their significance, and compare/contrast to accepted values, and perhaps speculate on how to do it better, within reason.
• Significant Figures: Be sensible here. If you are writing down all the numbers on your calculators display you are likely being absurd
• Avoid subjective evaluation Don't use phrases such as "we learned a lot," or "the results are good," or "this was a hard experiment." Stick to concrete statements such as, "our results are 5% greater than the accepted result."
• Results and Discussion: This is where you give your answers, discuss their significance, and compare/contrast to accepted values, and perhaps speculate on how to do it better, within reason.
• Conclusions: If you have a solid Results and Discussion section you usually would not need a formal Conclusions section. Don't repeat the results, but interpret the significance of them. Did you prove (very, very unlikely) or disprove anything? Did you support something? Did you meet the objective? Avoid subjective evaluations of your results or the experiment. For example, dont say Our results are good.
• Length: Make your case concisely. After college you will find yourselves in the situation of having a limited time or space to present your case. Learn to concentrate on the important issues. Sentences tend to be much shorter than in literary writing.
• Overall: Ask yourself if someone who wasnt there would be able to follow your report. Does it have logical flow, and enough information?

Grading
You will receive a grade of from 0 to 10 on each laboratory exercise. I consider an 7-8 to be a "B", and a 5-6 to be a "C." I do not have to give every member of the group the same grade on the report. Your grade will be based primarily on your written laboratory report but may be weighted by other factors, including:

1. My evaluation of your manner of performance and technique.
2. Your contribution to the efforts of the group.
3. Appearance of the lab report.

Safety in the Lab

First and foremost is safety. Always! The following guidelines have been developed and you need to become familiar with them. First, learn these phone numbers, especially the first one!

Do NOT dial 911 from a campus phone! Doing so will result in emergency personnel showing up at some distant building that houses the telephone switching gear for the College of Charleston and the Medical University of South Carolina.

Safety in the laboratory and classroom is everyone's concern and is mostly a matter of maturity and attention. Most physics experiments and demonstrations use simple and safe equipment. Don't allow this to lull you into a false sense of security. Instructors may eject students from a day's lab exercise when those students violate the safety rules. This will probably result in grades of zero for the day for the ejected students.

Safety and Lab Rules

You, as the student, have the responsibility for following lab rules and maintaining safety in the lab. There will be rules given to you by your lab instructor. These rules will include

• Be aware of yourself.
• You must be properly clothed with attire that will not catch on equipment or keep you from taking measurements.
• You must have closed-toe shoes.
• You must keep your bag and/or books out of the way of others on the floor or on the lab tables.
• You must use safety equipment, i.e., safety goggles, when instructed to do so by your instructor.
• Be aware of your equipment.
• Take only the equipment that you have been instructed to use in the lab.
• Use the equipment in the way that you have been instructed.
• If equipment is not working properly, set it aside and inform your lab instructor immediately.
• Return equipment as instructed by your lab manager.
• Be aware of others.
• When running a lab make sure equipment does not take the space of other lab groups.

First Aid Kit: Every Classroom is equipped with a first aid kit in the third drawer in the teacher desk at the front of the room. It is checked and refilled on a routine basis. If you find something lacking in the kit please notify one of the lab managers.

Sharps Boxes: If glass is broken in the lab. Then please dispose of it in the sharps box. There is a sharps box in room 107 on the counter and room 125A on top of the file cabinet.

Safety Glasses: Safety glasses are stored in cabinets in rooms 108 and 107.