1 Physis Cousewae oden Physis Enegy and oentu Relatiisti oentu: p γ Kineti enegy: K. E. ( γ ) Auxiliay equation: E + 4 p whee is the est a...
1 Physics 342: Modern Physics Final Exam (Practice) Relativity: 1) Two LEDs at each end of a meter stick oriented along the x -axis flash simultaneous...
1 Physics 2170: Modern Physics Professor: John P. Cumalat Office: Duane F321 (Gamow tower) Phone: Course Web page: Classroom: HUMN 1B50 (here) Text...
1 College of William and Mary W&M Publish Arts & Sciences Open Educational Resources Arts and Sciences Summer 2015 Physics 201: Modern Physics...
Physics 2150 - Experimental Modern Physics Spring 2015 Lecturer: John Cumalat, Office: Duane F-321 email: [email protected], Phone: 303-492-8604 Office hours: By appointment or just try stopping by Lab Coordinator: Scott Pinegar, Office: Duane G-2B87, Phone: 303-492-6840 Teaching Assistants: Adam Green email: [email protected] John Houlton email: John [email protected] Office hours: By appointment or just try stopping by Website: http://www.colorado.edu/physics/physics2150/phys2150 sp15/ Introduction: Physics 2150 is an exercise in experimental physics. The course is based on a series of experiments that, over the course of the twentieth century, led to much of our understanding of the physical world and laid the foundation for technologies ranging from microelectronics to magnetic resonance imaging. In Physics 2150, there will be more emphasis on writing than in Physics 1140, the introductory lab. The student is expected to compose clear statements of the objective, procedure, and conclusions for each experiment. This requirement reflects the fact that in science, communication is as important as laboratory work. Attendance: To complete the work, you must attend at least 12 laboratory sessions in G2B70 and turn in the homework assignment. (There will be a total of 14 laboratory sessions scheduled.) You must take all experimental data during your regularly scheduled lab period. If for some reason you must come to the lab outside your scheduled lab time, check with your lab instructor first so that arrangements can be made. Radiation Certification: All Physics 2150 students are required to complete radiation training for use of sealed sources before their first lab section. The radiation safety training tab has more information. Selection of Experiments: There are 13 experiments set up in the laboratory, listed below, most of which are set up in duplicate. You are expected to complete six of these experiments during the semester. You may choose any experiments subject to the condition that two must be from the group marked with asterisks at the end of these instructions. You should begin the semester with the non-asterisked experiments (ie. the asterisked experiments are not available in Week 1). The maximum grade you can receive per experiment is 20 points. Thus, the maximum number of points you can accumulate from six laboratory experiments in Physics 2150 is 120. If you choose the Compton experiment or the Millikan Oil Drop experiment, then it is possible to earn an additional 5 points. There is a sign up sheet for your laboratory section posted on one of the two interior doors along the north wall of the Physics 2150 lab area. Schedule yourself for a particular experiment by placing your name in the proper entry space for the relevant time period. Remember, allow 1
yourself two weeks for all experiments except the Millikan and Compton experiments which require three weeks. There are two independent set-ups of most experiments, and two people can work as partners (see discussion below), allowing a maximum of 4 people to work on most experiments at one time. If you choose not to do two of the experiments with asterisks, at the end of the semester, the points from your two lab reports with the highest scores will be counted only 50total points you can get in the course would be 100 out of 1q20. If you only do one lab with an asterisk, the maximum possible is 110 out of 120. Schedule: The first lecture is on Tuesday, January 13, 2015. Lectures are held in Duane G130 at 4pm and all students in Physics 2150 should attend. The laboratory sections will meet beginning Thursday, January 15, 2015. There are 14 weeks in the Spring semester during which the Physics 2150 lab will be open. The last lab day is Tuesday, April 21, 2015. After you have completed an experiment, your lab notebook should be turned in for grading. You should complete your experiments and submit them for grading on a regular basis until you have completed the six experiments as described above. Due dates are below: First report by 4:00pm Friday, January 30, 2015 Second report by 4:00pm Friday, February 20, 2015 Third report by 4:00pm Friday, March 6, 2015 Fourth report by 4:00pm Friday, March 20, 2015 Fifth report by 4:00pm Friday, April 10, 2015 Last report by 4:00pm Monday, April 27, 2015 The object of having a schedule is to have you become familiar with the grading system at an early stage and to provide feedback on how you are progressing in the course. These are definite deadlines and credit will be deducted for late reports. In this course the reports are typed reports that are submitted along with your lab notebook. See the section of these instructions on Organization of Lab Notebooks. Reports should either be handed to the instructor during the laboratory period or placed in the “black box” by 4:00pm of the day they are due. Lab reports may be submitted for grading anytime before the above dates and you are encouraged to turn them in for grading on a regular basis, as they are completed, without waiting for deadlines. Lectures: There will be six lectures given on consecutive Tuesdays in Duane G130 at 4pm, beginning January 13, 2015. The lectures will be based on chapters 5 through 9 and chapter 11 of John Taylor’s book, “An Introduction to Error Analysis,” and will treat examples of error analysis as applied to specific Physics 2150 experiments. NOTE: Physics 2150 students should be familiar with the material contained in chapters 1 through 4 of this text. The purpose of the lectures will be to give you a basic introduction to experimental analysis. The quality of your lab reports and a significant component of your course grade will depend upon the way in which you analyze your data and assess the contribution of various errors. A set of homework problems from the lectures will be assigned. Homework Assignment: The homework assignment related to the material presented in the lectures will be handed out at the last lecture. The assignment will consist of problems of the 2
types at the end of Chapters 5–9 and 11 of Taylor’s book “An Introduction to Error Analysis” but will often utilize concepts from many chapters. Your solutions are to be placed in the “black box” for grading. The homework should be worked individually and the deadline will be announced in class. The problems will be worth a maximum of 12 points. Grading: The letter grade you receive for this course is directly related to the number of points you receive on your laboratory reports and on the homework assignment. As stated previously, you can obtain a maximum of 120 points for your laboratory reports (plus up to 10 points for the 3 week experiments), 12 points for the homework assignment, and 3 points for completing the learnign surveys. Thus it will be possible to accumulate 145 points at the end of the semester. We try to have an average of 15 points out of 20 for each laboratory section for the laboratory reports. Generally if you receive a score that puts you in the upper half of the class you will receive an A or B. Late labs will be penalized at a rate of 1 point per weekday. Labs that are two weeks late will not be accepted. If you cannot meet a deadline, then contact your TA as soon as possible. In order to receive a withdrawal or an incomplete you must have certifiable excuse for not completing the course and you must make an explicit arrangement with your lecturer. If you are not doing the required work, drop the course. This advice is offered with your protection in mind. Should a problem arise which forces you to drop the course after the deadline, you will receive an F rather than an incomplete if you have a failing grade at the time. Procedural Matters: 1. You will keep possession of your lab notebook outside of class, except when you submit it to your instructor for grading. 2. Each week your instructor will check with you during the lab to see if you have taken data. Your data must be initialed by your instructor. Your instructor will record: the date, the fact that you’ve taken data, your partners name, should you have one, and the experiment title. In the event you are working in the lab when no instructor is present, then have the lab coordinator, Scott Pinegar, initial your data. 3. Should your instructor fail to check your data during class, it is your responsibility to see that it is done before you take your lab book out of the lab. A student who wishes to have an experiment graded which contains significant data that have not been properly signed by the instructor can expect a maximum grade of 15 out of 20 possible points on that experiment. 4. The work you hand in must be your own. Although it is entirely permissible for you to take data in partnership with another student, and to discuss your lab work with other students and instructors or anyone else, the work you present for grading must be the product of your own effort. No two students should present identical analyses and conclusions. 5. When you have completed an experiment and have the laboratory report written, leave your lab notebook in the “black box” in front of the lab coordinator’s office. Your experiment will be graded and your notebook returned to you at the next meeting of your laboratory section. 6. Upon the return of your notebook read carefully through the experiment that has just been graded so that you can benefit in future reports from the instructor’s comments. 3
Preparation for Lab: Since the time in which you have access to the laboratory is limited, you should prepare yourself for the lab by reading and studying the experiment instructions before coming to class. There are video-tape presentations of the experiments which are available for viewing. Be sure to read any pertinent information posted near the experiment since some of the experiments have changed since the instructions were last revised. Once you have decided on an experiment then you must sign up to reserve the experiment for yourself. If you have prepared for the experiment, but you have not reserved it ahead of time and it is already taken, then you will be asked to prepare for another experiment. Lab Partners: You may perform the experiments either individually or with a partner. Groups larger than two are not permitted and only one experiment may be done with the same partner. If you work with a lab partner you should analyze the data separately. When working with a partner make sure you each have an equal share of the actual data taking responsibilities. Organization of Lab Notebooks and Reporting Experimental Results 1. Write on the right hand pages only. Leave the left hand pages for the instructor’s comments. 2. Use the first page for a table of contents. Enter the title and page number of each experiment. Leave a space for the grade. 3. Number all the pages consecutively in ink. Do this the first laboratory session. Never remove a page. 4. The first thing written on any page (during data taking or write-up) is the date. 5. Write your name on the bottom edge of the notebook in large visible letters. 6. Date each page as it is used and date the start of each day’s work. 7. Each lab period, record the name of your lab partner, or make an entry stating “no lab partner.” 8. Primary Data: Primary data comprise all measured quantities that you collect in the course of an experiment. Such data should be recorded directly in your notebook; use a pen. Never erase primary data. If you make a mistake while taking a measurement, draw a line through the corresponding entry and write a brief explanatory comment. It is very difficult for most students to collect a neat and orderly primary data set when performing an experiment for the first time. If you prefer, you may record your primary data, either on a page (or pages) before the first page of the report, or in a section of “dedicated” pages at the end of your notebook. There is one caveat: If you choose this approach, you must copy the entire data set into its appropriate place in the report, and you must refer explicitly in your report to the page locations of the primary data. 9. Format to use when writing Physics 2150 lab reports: The purpose of the record of an experiment is to explain clearly and concisely what you are trying to do, what you actually did, what you actually observed, and what you concluded from your observations. It is essential that you write in clear, uncluttered, unambiguous English. Aside from this general requirement, there is no preferred format for reporting scientific/engineering results; as your career develops you will decide which reporting style works best for you. However, in Physics 2150 we require you structure your reports according to the topics and order below. The text should be written using any Word Processing Program or a 4
technical language such as Mathemtica if you prefer and format properly. All analysis plots shuld be made using Mathematica, or some equally capable program (not Excel). Feel free to draw diagrams by hand, of they can be made on the computer. You can use annotated snapshots of the apparatus, but note a picture is not always a substitute for a diagram. You cannot “snip” diagrams from the lab manual; the diagrams must be made by yourself. We feel learning how to create diagrams that illustrate your points is an important part of this course. (a) Experiment Title (b) Objective: - A one or two sentence description of the basic intent of the experiment. (c) Idea: Describe qualitatively in a few sentences the idea (or ideas if there are several distinct parts) of the experiment. What are the essential elements of the experiment that (in principle) will enable an effect to be observed or a quantity to be measured? There should be some physics in this section. (d) Apparatus: Include a labeled schematic drawing, indicating how the experiment works. Briefly describe the function of any unusual (special purpose) apparatus. (e) Procedure: This should consist of a summary of the process you followed while carrying out the experiment. Note unexpected occurrences. Discuss any special problems of measurement and the approach you took to solve them. This section should contain enough detail to enable you to return after a six month hiatus and repeat the experiment without referring to the lab manual. Use your own words (don’t simply paraphrase the related section in the lab manual). You should describe what you actually did in the first person. (f) Data Analysis and results: This is a key section of your report. The complete data set appears here; the data are analyzed and the sought-after experimental results are derived and reported with their associated experimental uncertainties. You should incorporate: i) Plots of data or results (title, axis labels, units and scales). The use of tables is strongly recommended. ii) Calculation of results. A complete, detailed numerical sample calculation of each type, including units and conversion factors must be included. If computer calculations are used, the printed computer output with complete identification of quantities written on it should be taped into place within this section and explicitly referred to at an appropriate point in your report. iii) For each experimental result you report, a correct estimate of its uncertainty. The complete expression of a final result will consist of your “best value,” the estimated uncertainty, and the proper units. The uncertainties should include statistical and systematic uncertainties separately. (g) Conclusions: A discussion which summarizes your results, compares them to accepted values, treats the basis for assigning errors if you choose not to discuss this in the previous section, etc. When you compare your results with their related “accepted” values, be aware that the word “discrepancy” has a meaning different from “error.” In addition to determining the percent difference with respect to the accepted value, you should determine the discrepancy (using the combined statistical and systematic uncertainty) and the significance of the discrepancy. If appropriate, you can mention the important source(s) of uncertainty and possible ways to improve on them. If you observed anything puzzling, or if you care to digress about possible hidden sources of error that you suspect might explain an unexpectedly large discrepancy, then do it here. Don’t simply muse about possibilities; if you 5
have suspicions, you should back them up with reasonable quantitative estimates. You can lose points by simply making unsubstantiated or incorrect guesses. Things to avoid in writing your report: 1. Blaming the equipment: Your task is to produce the best measurement possible given the equipment available. The limitations of the equipment should be treated scientifically, as terms in your uncertainty calculation. Do not use any section of the report for complaining. 2. Vagueness: All language should be precise. Avoid words like “approximately,” “sort of,” et cetera. You can lose points by simply making unsubstantiated statements. Never attribute uncertainties to nondescript causes like “experimental error.” 3. Grammatically poor English: You’re expected to learn how to write professional reports. Good language is a critical aspect of this training. Supplies: Both the laboratory manual “Introductory Modern Physics Experiments,” and the lab notebook in which you will write laboratory reports, will be handed out free in the lab. These are provided by your student course fees. Therefore, the only text you will need to buy, if you do not already have a copy from Physics 1140, is “An Introduction to Error Analysis,” by John R. Taylor, University Science Books, Second Edition, 1997. Additional Comments: • Student laboratory manuals will generally be kept by the department. If you would like your lab notebook back, you can collect it the following semester from the lab area. • Calibration for instruments used in all experiments can be treated as follows: – Oscilloscopes: ∆V/V = ± 0.05 – Analog Voltmeters and Ammeters: ∆V/V = ∆I/I = ± 0.03, unless otherwise stated. – Digital meters: The calibration uncertainty is posted by the apparatus.
Physics 2150 Experiments
∗ ∗ ∗ ∗ ∗
No. Name 1. Charge-to-Mass Ratio of the Electron 2. The Millikan Oil Drop Experiment 3. Michelson’s Interferometer 4. Rest Mass of the K 0 Meson 5. The Photoelectric Effect 6. The Compton Effect 7. Electron Diffraction from Crystals 8. Emission Spectra and the Balmer Series 9. The Franck-Hertz Experiment 10. Radioactive Decay of 220 Rn 11. Magnetic Torque 12. The Hall Effect 13. The Zeeman Effect
Weeks 2 3 2 2 2 3 2 2 2 2 2 2 2
Two of your six experiments must be ones marked with a ∗. However, these are more difficult and should not be attempted as the first experiment of the semester. Hints for Specific Experiments Remember to look for additional notes or values posted on or near the apparatus. E-1 e/m (2 setups)- Make several independent measurements of Io at the lowest voltage. E-2 Millikan (2 setups) - Do not attempt this experiment as your first. E-3 Michelson (2 setups) - Take precautions against micrometer backlash in this experiment. E-5 Photoelectric Effect (2 setups) - you should use the least-squares straight line fitting routine to analyze your calibration and voltage vs frequency data. E-6 Compton Effect (1 setup) - This is an excellent 3 week experiment. E-7 Diffraction from Crystals (single setup) - Use nominal tube voltages of 6, 8, and 10 kV. The actual value to be used in computations is posted on the apparatus. E-8 Emission Spectra (2 setups) - This is the most precise experiment if done with care. In addition to determining an uncertainty in h based on the four “measured” values of h, you should determine expected uncertainty in hmeas based on your calibration curve and your uncertainty in determining the refraction angles. E-9 Franck-Hertz (2 setups) - Draw a sketch of a typical “scope” pattern for both parts I and II. Clearly identify what is being plotted. In part I record the voltmeter readings corresponding to each current peak. Then take the differences between neighbor peak voltage values. E-10 Thorium Decay (1 setup) - Remember rules for Poisson statistics to get uncertainties. E-11 Magnetic Torque (2 setups). No special hints. E-12 Hall Effect (one setup) - You may observe some evidence of a non-linear VHall vs B dependence at higher B values. This is to be expected. You may wish to use the least squares routine to determine RH . If you do not observe significant non-linear behavior at high B, then you should sit back and think before leaping into analysis. 7
E-13 Zeeman Effect (single setups). No special hints.
History of the Development of Modern Physics bold: in this lab; italic: theory 1879 Stefan radiation law 1879 Hall Effect 1885 Balmer Series 1887 Michelson Morley experiment 1887 Electromagnetic Waves (Hertz) 1893 Wien’s radiation law 1900 Planck quantum hypothesis 1900 Photoelectric Effect (Lenard, Millikan) 1902 Zeeman Effect (Zeeman, Lorentz 1905 Einstein quantization of light 1905 Einstein Special Relativity 1909 Millikan Oil Drop 1911 Nuclear Atom (Rutherford) 1913 Bohr Model 1914 Franck-Hertz 1923 Compton Effect 1924 deBroglie hypothesis 1925 Davisson-Germer Electron Diffraction 1926 Quantum Mechanics (Schr¨ odinger, Heisenberg) 1947 Discovery of Neutral Kaon
Other policies set by the University Disability issues: If you qualify for accommodations because of a disability, please submit to me a letter from Disability Services in a timely manner so that your needs may be addressed. Disability Services determines accommodations based on documented disabilities. Contact: 303-492-8671, Willard 322, and http://www.colorado.edu/disabilityservices. Religious observances: Campus policy regarding religious observances requires that faculty make every effort to reasonably and fairly deal with all students who, because of religious obligations, have conflicts with scheduled exams, assignments or required attendance. See full details at http://www.colorado.edu/policies/fac relig.html. Please contact me if you will miss a lecture or laboratory session due to a religious observance to arrange an appropriate remedy. Classroom behavior: Students and faculty each have responsibility for maintaining an appropriate learning environment. Students who fail to adhere to such behavioral standards may be subject to discipline. Faculty have the professional responsibility to treat all students with understanding, dignity and respect, to guide classroom discussion and to set reasonable limits on the manner in which they and their students express opinions. Professional courtesy and sensitivity are especially important with respect to individuals and topics dealing with differences of race, culture, religion, politics, sexual orientation, gender variance, and nationalities. Class rosters are provided to the instructor with the student’s legal name. I will gladly honor your request to address you by an alternate name or gender pronoun. Please advise me of this preference early in the semester so that I may make appropriate changes to my records. See polices at http://www.colorado.edu/policies/classbehavior.html and http://www.colorado.edu/studentaffairs/judicialaffairs/code.html#student code. Honor code: All students of the University of Colorado at Boulder are responsible for knowing and adhering to the academic integrity policy of this institution. Violations of this policy may include: cheating, plagiarism, aid of academic dishonesty, fabrication, lying, bribery, and threatening behavior. All incidents of academic misconduct shall be reported to the Honor Code Council ([email protected]; 303-725-2273). Students who are found to be in violation of the academic integrity policy will be subject to both academic sanctions from the faculty member and non-academic sanctions (including but not limited to university probation, suspension, or expulsion). Other information on the Honor Code can be found at http://www.colorado.edu/policies/honor.html and http://www.colorado.edu/academics/honorcode. Discrimination & sexual harassment: The University of Colorado at Boulder policy on Discrimination and Harassment http://www.colorado.edu/policies/discrimination.html, the University of Colorado policy on Sexual Harassment and the University of Colorado policy on Amorous Relationships applies to all students, staff and faculty. Any student, staff or faculty member who believes s/he has been the subject of discrimination or harassment based upon race, color, national origin, sex, age, disability, religion, sexual orientation, or veteran status should contact the Office of Discrimination and Harassment (ODH) at 303-492-2127 or the Office of Judicial Affairs at 303-492-5550. Information about the ODH and the campus resources available to assist individuals regarding discrimination or harassment can be obtained at http://www.colorado.edu/odh. 9