Physics 370 — Experimental Physics
Fall 2016, Room 209 HWWE, MWF 2:00-5:00
(Ongoing Minor Revisions)
Dr. Jeff Wragg Office: 209 JC Long, Office hours: TR, 10:00-10:50
Building/Lab Access phone: 953-5609 Emergency phone: 953-5611
email me: email@example.com
or send me an anonymous web-based email
Elements of a Good Experiment
- Problem statement
- Literature search
- Design of the experiment
- Design of the equipment
- Execution of the experiment
- Maintaining records
- Analyzing your data
- Recognizing errors and their impact
- Communicating your results
Equipment review and introductions may include
- Power Supplies
- Lock-in Amplifier and chopper
- Gamma spectrometer
- Electron Microscope
- Compact Optical Spectrometers
- Web resources
- Computer programs
- LaTeX—for document preparation
- Inkscape—for technical illustrations
- Mathematica—for data processing and graphics
- Other graphing programs
- Formal analysis of errors
- Data fitting
- Data evaluation
Writing a Paper
- The audience
- Tables and illustrations
There is no formal text for this course, rather it is a compilation of notes, handouts, and web resource materials. It is absolutely vital that you take comprehensive notes during the class. This semester is your opportunity to develop your physical intuition in the context of investigating a problem. You will get to formally state the problem, design and construct the investigation, analyze the data, draw appropriate conclusions and communicate the results. In all respects a more polished performance is required of you in this class than you have had to demonstrate in the past. This course represents a transition for you, from student to professional. You need to develop a professional sense of responsibility for the work you produce, and for the process of producing it. Much of the evaluation of your work (by me) is from a professional perspective. Think of yourselves as doing work for pay, and I am the boss. Don't turn in a student product, turn in a professional one.
Please communicate your questions, comments, and problems to me. I am pleased to see you any time you can drop in. Please leave me a note if you can't find me.
It is your responsibility to learn—to do the work using available resources, taking responsibility for finding the knowledge and equipment you need. You get to work in groups and alone. Take this opportunity to show to everyone that you can handle the responsibility. Historically, the biggest problem encountered by students in this course is poor time management. You are given some freedom to schedule your assault on the problem—don't abuse this freedom.
Be courteous to others. We have limited space and equipment, so don't expect to set up an experiment and have sole use of the equipment and space for more than a couple of days. You may need to coordinate with your classmates for access to some equipment. There may be times when courtesy should be extended with regard to opening the door and turning on lights. You are expected to put equipment away and otherwise keep the experiment areas clean and tidy.
Preparation for the Course
Modern Physics (phys230) is a prerequisite for this course. You will need to maintain a working knowledge of the physics and mathematics at the level of physics 111/112/230. Laboratory experiences in physics 111/112 are a valuable knowledge and experience base for this course. Review your laboratory experience. Look over old reports to identify skills you need. Of course by now you should have completed English 110. If you haven't, then don't take this course. Finish English first.
I also assume that you have computer skills, including email, using the web, word processing, Mathematica, spread sheets, and other generic, scientific computer tools. We will enhance your skills with all of these.
We will have formal classroom time, especially early in the semester. It is important that you apply your attention to these presentations as they will be vital to your experiments. Students will be required to pick a professional track—physics, astronomy, or meteorology. While everyone does the same first experiment, there are computational, equipment and write-up differences between the professions.
There will be two phases to the course.
- Lab skills development and proficiency exercises
Perform experiments and write reports
- Simple circuits/multimeters/power supplies/oscilloscopes/function generators
- LaTeX, for document preparation
- Inkscape, for technical illustrations
- Curve fitting
- Error propagation
- Graphical representation of data
- e/m ratio for electrons—everyone does this one
- Another experiment—you get some choice of which one. (but I reserve the right to assign)
- Final experiment—you get some choice of your experiments (but I reserve the right to assign).
- Peer editing and re-writing the lab reports
- Oral presentations
I may allow you to work in groups of up to three. In no case will you work with any specific individual on more than two of your experiments. I reserve the right to restrict your choice of partners, and I may even encourage or require you to work alone.
Absences and Tardiness
On the occasions we have formal classroom time you are responsible for the material presented. Contact a classmate for the notes.
Preparing to do an Experiment
There are several steps to take before you actually do an experiment.
- Come up with an experiment
- Gather more information, especially get a good grasp of the underlying physics.
- Familiarize yourself with the equipment
- Look for more information in your text books or elsewhere
- Talk with me before finalizing your choice
- Study the experiment
- Map out a strategy
- Locate necessary equipment
- Convince me you know what you are about to do
You will maintain a notebook of your lab experience. It is an up to date diary of your lab work. It should contain dates, names, times, equipment lists, diagrams, raw data, musings, ideas, sketches, casual observations... One good model is to write only on the right hand page, and use the left hand page to insert graphs and tables or other computer-generated information. They may be taped or glued in place. In very formal cases one would sign and date across the boundary of such inserted items. The lab notebook is the basis for your lab report, which should contain nothing that isn't in the notebook, at least rudimentarily. It should be decipherable by your colleagues, but is intended to be a working document, not a finished product. I will examine these notebooks from time to time without notice.
Should any of you prefer to do some online, electronic sort of lab notebook, I am quite willing to let you do so. This is the 21st century, and many research organizations do it electronically. I must have access though.
Here are some guidelines:
- One or two blank pages for a table of contents
- Number the pages
- Never tear out pages
- Date the entries
- Write only in ink
- Put in clear titles for each experiment
- Clearly state the goal and motivation of the experiment
- Equipment list, and source, especially if you borrowed it
- Errors may be crossed out, but should still be legible
- No blank pages or large blank spaces, although you may choose to write on only one side of the page, but be consistent.
- Include relevant equations that you connect to your experiment
- Sketches are good, but make them schematic, not artsy
- Develop the mathematics of your experiment—Derivations which start with fundamental physics are appropriate
- Clearly indicate data processing and statistical methods used
- At some point you should have a clear, concise outline of your procedure
- Tell the reader what you did and why you did it
- Address problems and their resolution
- File name and location of computer files relevant to the experiment
- Computer printed figures and tables may be taped in.
- Speculation is good—make notes to yourself of things to try
- Clearly state the result
- Error analysis
- Proper attribution for external sources of information
The written products in this class are intended to help you learn to do professional, journal style articles. Communications to the professional community via journals are very different from other written products, for example, a "lab report" in most other lab classes has a very different audience and intention than the articles you write in this class. Similarly for a final grant report or final project report to a funding agency. Each has its purpose and audience, and are consequently very different from one another. It is vital that you understand the purpose, audience, format, and editorial standards for any written product.
Each student will produce and submit their own report, even though you may do the experiment as a group. While you may work closely together on the experiment, each student writes up their own report, in the appropriate format (i.e., using the LaTeX template suitable to their profession), and each student should be completely competent in the details of data manipulation and analysis. Reports are expected to meet the highest editorial and scientific standards. Pretend it is being submitted to a refereed journal for publication and that your job is on the line. The details of your format are dictated by those used in a journal you choose which is consistent with your career goals. The term "lab report" is somewhat of a misnomer, as you turn in a lab notebook, and your formal write-up is more of a journal submission format.
These formal reports are the focal point of your work. The experiment isn't worth doing unless its results are communicated to others. A generic, everything is OK, no significant errors, good layout, adequately conducted, reasonable conclusion lab will get you "B". Subtlety, insight, and cleverness can get you more. Lab reports are written up individually, even though experiments may be conducted as a group. It is inappropriate (i.e., it is considered academic dishonesty) to pass lab reports down to students in future classes, or to get them from previous classes.
The editorial guidelines used by the American Physical Society or American Astronomical Society will generally be followed unless you convince me that you should follow the guidelines of another organization. If your career goals and academic path are consistent with your case it will likely be fine with me. See example papers in journals such as Physical Review, or check out their online style guide, or the Astrophysics
Reports will ordinarily contain
- An abstract of no more than 100 words. A concise summary of your experiment and the results.
- A brief introduction clearly stating the physical principles involved and the goal of the experiment.
- Background and references, historical and/or scientific (Do not make this extensive).
- Clear description of the procedures and a schematic illustration of the experimental setup.
- Relevant data, graphical and/or tabular. Do not include extensive raw data.
- Description of the analysis of the data, the result, the uncertainty, and comparisons with generally accepted results
- Conclusions: what can you say based on your experiment? How does your result relate to the goal of the experiment? Is the theory upheld by the experiment? Do not make this a personal commentary on the experience you had doing the lab.
- Suitable primary references.
- An appendix with a summary of your statistical methods and tools
- An appendix with a summary of your computational methods and tools (that are not statistical in nature).
The Checklist— Pitfalls, Tips, and Hints...
Things NOT to include
- Abstract: comprehensive, informative, and includes the answer. No references in the abstract.
- Ask yourself: "What is the purpose of this section?" "What is the purpose of this paragraph?" "What is the purpose of this sentence?"
- The report should be written at the appropriate technical level—for your peers.
- Keep in contact with me during the experiment. Brainstorm with me. The more you tell me what you are doing the more likely I can save you some time.
- Tables and figures are usually best placed as soon as feasible after they are referred to in the text. Note that LaTeX has its own way of deciding where to put them, but you do have some influence over it.
- Start the write-up early in the experiment. It will help you decide what data you need, and may suggest extra experimenting.
- The word "then" is often misused/overused.
- Lead in to equations properly. Look in books and technical papers to see how one leads into an equation. Also, you must define all variables when they first appear.
- Use superscripts, subscripts and other typography appropriately.
- Use symbols, abbreviations, and language that are consistent with your professional identity.
- Include an answer and uncertainty, with appropriate significant figures, and units.
- When possible, compare your result with accepted results, and give a reference
- Appropriate significant figures
- It is probably best to write in the past tense.
- Figures—Keep them simple, make them schematic rather than artistic. They should be numbered and include a useful caption. They connect variables in the setup to variables in the math.
- Graphs—Should be simple, but complete, with axes labeled, and data points, and fitted functions distinct from one another. A figure should be numbered and include a descriptive caption.
- Do not include details we don't care about, e.g., "...we tried... but it didn't work...", the reader generally doesn't care about things that didn't contribute to the answer, or trivial details about instruments such as "We used detector number 3," or obvious things such as, "we turned the instrument on... we recorded the data..."
- Don't use contractions.
- Avoid "cute" words, i.e., ones you feel should be enclosed in quotes.
- Do not make subjective statements such as "our results are good." Be objective, and let the reader judge you.
- Do not give a list of materials/equipment/procedural steps.
In addition to the guidelines above, the following will be considered when assigning a grade to your report.
- Difficulty of the experiment
- Thoroughness of the experiment
- Creativity and originality
- Timeliness of your assault on the experiment
- Professionalism—care of equipment, clean up...
- Your level of effort
You will make oral presentations in several ways. On occasion you will be asked to give a 1-2 minute status report on your current experiment. This will likely be without notice. Finally, you will give a seven minute formal presentation, probably, but not necessarily, on your third experiment.
The formal presentation will be given during a final exam period for our class. The talks follow a standard presentation format used at scientific meetings. The talks will be seven minutes long (+/- 1 min), and use suitable, professional-quality visual aids. For a really good primer, see the MIT Sample. Another good set of tips for scientific talks.
- 7 minutes long, penalties for outside 6-8 minutes.
- Slides should be done using LaTeX or PowerPoint. I will give you a LaTeX Beamer template that is easy to adapt. LaTeX Beamer, another Beamer page, or LaTeX PowerDot, which I haven't used, but you may.
- Make text large and easily readable
- Don't have a lot of dense text
- Do use diagrams, graphs, and charts
- Talk to the audience. Do not read to them
- Have it visually appealing, but not distractingly so
- Make certain that everything is viewable by the audience. Note that some colors or color combinations don't work well with room-scale video projectors.
- Circuits and measurements proficiency exercise due Friday, 22 January, 5:20 pm.
- LaTeX-based Proficiency Exercise are due Wednesday, 27 January, 2:30pm. Email pdf to me.
- e/m ratio formal written report due 2:30 pm, Monday, 8 February.
- Bring three copies, two that are anonymous (no names). Peer editing in class that day.
- Re-writes due Monday, 15 February, 2:30 pm. One copy, as a pdf email attachment to me.
- Second experiment is due 2:30 pm, Friday, 18 March. Bring three copies. Or, email the pdf to me in time for me to print it, say no later than 10:00am. Peer editing in class that day.
- Re-writes due – a week later 2:30 pm, as a pdf email attachment to me.
- Oral presentations Exp 3 – You will present either Monday the 25th or Wednesday the 27th, 4-7 pm (Location TBD). Volunteers will be solicited first, to see if we can balance each day. Then names will be drawn randomly if necessary.
- Experiment 3 write-up is due – noon, Friday, 29 April (attach pdf to email, make sure I acknowledge receipt)
The above due dates are subject to change a little, but there will be ample notice. Late assignments may be accepted (at my whim), but will ordinarily be penalized, more so each day they are late. It is especially important that you turn in the first write-ups on time so you can benefit from peer editing.
The accumulation of grades is as follows. We do three experiments. For experiments one and two you submit an original lab report, then we do some editing, and you submit a revised version. The original and its revision are each graded, and carry the same weight. The third experiment is a one-shot effort—no revision. In the overall grading scheme the first experiment carries a weight of 2, the second a weight of 4, and the third a weight of 6.
I assign letter grades to papers, lab notebooks, and talks. The letter grade is assigned a number as in the College's grading scheme (A=4.0, A- = 3.7...). Proficiency exercises and quizzes are graded on a 10-point scale, which is rescaled to a 4.0 scale by dividing by 2.5. The weighted average is calculated to determine the final grade. Below are the relative weights of the pieces of your semester grade.
|Lab reports|| 70%|
|Lab Notebook|| 5%|
|Quizzes and proficiency exercises|| 15%|
|Oral Presentation|| 10%|
|Total|| 100% of course grade|
Disposal of submitted work
I will dispose of old, unclaimed reports, lab notebooks, and other submitted materials about a month into the next semester, so if you want them, please contact me before then.
Course Pre/Co-requisites: phys230, or phys225 or permission
Learning Objectives —
This course endeavors to aid the motivated student in the following tasks:
Learning Outcomes —
- Preparing an article, based on experiment, that adheres to basic scientific writing standards.
- Learning the elements of experiment design
- Learning the use, operation and limitations of experimental equipment
- Identify experimental limitations
- Learning to be a critical observer.
- Learning to analyze statistical aspects of experimental physics.
- Draw valid conclusions from your results
- Preparing a scientific talk, based on experiment, that adheres to professional presentation standards.
- Learning the professional standards associated with doing ethical work in the physical sciences.
At the end of this course, successful students will be able to:
Accommodations for Students with Disabilities —
- Define and produce a model of a physical system
- Create a model of the measurement system
- Analyze measurement data
- Produce effective graphical summaries of data and results
- Design the experiment and apparatus
- Identify problem issues and design troubleshooting strategies using the principles of physics
- Apply computational tools to analysis of data
- Select and use appropriate test and measurement equipment
- Construct and deliver effective oral and written communications in a professional manner
- Analyze, identify and quantify uncertainties and errors using statistical methods
- Assess and defend conclusions based on your experiment
Any student eligible for and needing accommodations because of a disability is requested to contact me as soon as practical or as soon as you have been approved for services so that reasonable accommodations can be arranged. I'm easy to get along with.
Academic Integrity —
It is expected that you will adhere to the university's honor code and student code of conduct, as can be found in your student handbook.
23 Aug 2016