Physics 331 Lab: An Introduction

 

You’ve spent many hours in an academic laboratory setting, but this experience is intended to be uniquely practical, often challenging, but ultimately rewarding.

Creative thinking, observing physical phenomena under controlled experimental conditions, collecting and processing data quantitatively and accurately, and experiencing the challenges of collecting information in the face of experimental error and variability – this is the intent.

Gaining experience in designing an experiment to answer a question is the goal of several labs. We give you a question and your team designs, through the use of creativity and background scientific knowledge, a way to measure the proposal in an effort to answer the question. Considering how your experimental design affects the certainty of your results will be of great importance.

Lab content often comes before the material is covered in lecture. Consider this a benefit: Realistically, you often have no idea what will happen and must explore a phenomenon experimentally. Discovering the behavior without knowing the answer beforehand (e.g. all real scientific experiments) is a skill to be gained in this instance. 

Your results matter, but the quantitative validity of your results is equally important. Repeated experiments never give the exact same results: variation is inevitable. But an “answer” must be submitted, right? To combat variation, the “answer” should always include a range of values which represent potential variation. You conducted the experiment in a unique way. Consider where the possibility for variation(s) lies and incorporate this into your “answer” mathematically or qualitatively. 

Learning how to share results and ideas is part of the scientific-process.  You will present your results to the rest of the class, have them comment on your results, and – likewise - you will comment on their results.  The process of many people analyzing and thinking about everyone’s work eventually leads to the correct result and correct interpretation. This often occurs through a scientific community/organization in the form of published papers or presentations at seminars or conferences. Consider peer-evaluation a mild introduction to critical peer-analysis aiming to produce ‘the best science’.

 

The Experiments

Prior To Lab:

Designing, carrying out, and presenting your results can be time-consuming. Fortunately, you will have two weeks to conduct most of the labs. 

Read the Lab Before You Come-In:

 

While You Are in Lab:

Document what you are doing in a lab-report-format as you proceed throughout the experiment.  Documentation must be shared with your lab partner(s). Results must be retained by all parties involved. Consider utilizing mediums like Google Drive to stay connected.

 

 

Lab Reports

 Lab reports fulfill a number of purposes. The following are of greatly emphasized throughout the course:

1.        Conveying an understanding of the goal, describing methods, and portraying associated theories.

2.        Reporting experimental results, interpreting their meaning, and exploring the reason for error.

3.        Presenting information in an orderly and logical manner; neatly reflecting professionalism exhibited in respectable publications.  Using the appropriate number of significant figures, including units, and labeling graphs appropriately are examples of such conduct.  

4.        Communicating in a clear and unambiguous manner (i.e. present as much information with the least amount of space). Imagine that you are the reader and want the bottom line and the main point – not unnecessary filler. The report must be completed in accordance with the syllabus - containing only the necessities.  Small-font, crowding, and margin-expansion is unacceptable. 

Your grade will reflect how well you have achieved these expectations.

*** Outline of a Typical Lab Report:

Use common sense as all the contents listed may not apply to each laboratory report.

1)      Goals:  Briefly state and describe the goal of the experiment to be performed.

2)      Experimental Approach:  Describe the strategy used and explain the logic of this strategy. This MUST include a professional description of the methods used. Be concise. A ‘scientific-individual’ should be able to repeat your experiment based on your methodological-descriptions. Do not explain the obvious, but include all deviations from normal procedure.

3)      Theoretical Expectations: Provide a theory which (often mathematically) models the experiment and provides a reasonable prediction of the results based on such theoretical model.

4)      Results Presentation:  Include tables and graphs near the corresponding text (NOT at the end of the report). 

5)      Discussion:  Interpret your results, discuss the limitations of the methods used, explain agreement or disagreement between experiment and theory, and explore changes which, in hindsight, might improve the results. Depending on the circumstances, discuss anything else that may be pertinent in retrospect. 

Participation in Class Discussion

Critically evaluating your own experimental design is hard! It is difficult to see how you could improve your experiment, and it is natural to believe that your design is the best design (if in reality it is not). This is why we hold a class discussion during each lab—to help you re-evaluate your experimental design. In doing so we hope that you develop a sense of your own bias. In other words, try to eliminate the natural tendency to make subjective ‘assumptions’ that potentially work against the objective.

A fair portion of your grade depends on participation in both class presentations and discussions at the end of the lab session.  We are looking for you to make significant contributions to other groups’ understanding of their lab, not just raising your hand and asking “why didn’t you take more data?”

 

Grading

Your lab-grade is essentially one-fourth of your overall grade for the course. The grade is based 1) on team lab reports, 2) on your individual participation in the lab, and 3) on your participation in the collaborative class discussions during lab. ** Your grade will not depend on whether your experimental results align with theoretical expectations or accepted standards. Your grade will depend on how well you conceived and carried out the experiment.

 

Attendance

Attendance at every lab is mandatory.  Contact your uTAs and/or the professor if you anticipate missing a lab session. With a VALID WRITTEN EXCUSE, one may perform a makeup activity at the end of the semester which will take at least two hours and may involve doing a novel lab, evaluating data, etc. You may participate in a makeup lab for a maximum of one excused absence. Without a valid written excuse, you will get a zero for the particular lab. You may receive a failing grade for the entire class (both lecture and lab) if more than one lab session is missed.