PH4152/6152 - Modern Physics Lab

Catalog Data

Six hours Laboratory. Scientific report writing. Experiments in modern physics, optics, and classical physics.

Prerequisites By Topic



Graduate Students

Graduate Students taking this course as PH 6142 or PH 6152 must make a significant improvement in the usual method on at least one experiment. This may require a literature search.


Reports should be brief, neatly typed, and well written. They should, where applicable, contain the following: (1) a brief introduction; (2) a diagram neat and detailed enough to make the procedure almost obvious; (3) a brief discussion of procedure (This is not necessarily a separate section; it can be integrated into a narrative about the experiment. Do not repeat detailed instructions you may have followed unless they are unusual. You don't have to report everything you tried that didn't work; you may decide to report mistakes that clarify the physics); (4) your results; (5) an estimate of your confidence in your results with justifications; (6) comparison with appropriate theoretical predictions; (7) a discussion of improvements you have made and others which you suggest; and (8), as footnotes or endnotes, the sources of anyone else's ideas that you have borrowed or referred to.

Assume that you are writing for someone who has the same general knowledge of physics that you have, but who has not done or read much about the particular experiment you are reporting.

Avoid having your report seem like a filled out form. Also avoid including details which would be obvious to anyone in a position to read the report intelligently. But don't make him/her guess at important details. Contrary to a common misconception you do not need to avoid first person.

Besides being more direct, first person makes dangling participles easier to avoid. Do not wander, for no good reason, between active and passive voice. Pronouns need clear antecedents. Don't use "it", "that", "which", etc. unless word order makes the pronoun's antecedent obvious on the first reading. Otherwise, use a noun instead.

See a physics journal such as American Journal of Physics for examples of good reports and appropriate use of footnotes or endnotes. There is an AIP Style Manual that has useful guidelines. I have a copy and the library has one.

Every report should be edited carefully before it is handed in. It should be clear and grammatically correct. It is not uncommon for a scientist to rewrite a paper a dozen times before it is published. You should do at least a couple of rewrites on every report before handing it in.

Usually, you should hand in your report on a completed experiment before starting another experiment.


Graphics should be done on the computer if you are skilled enough to make this method better than doing drawings neatly by hand. If you do drawings by hand, do them neatly in black ink. You may find it helpful to first do the drawing in very light pencil; go over the lines with ink and then erase any remaining pencil lines. Usually it is better to make equipment drawings schematic rather than pictorial. Graphs should be very neatly drawn with scales chosen so that most of the page of graph paper is used. You are encouraged to use a spreadsheet or other software to generate graphs. Either put drawings and graphs near where they are first referred to in the text or collect them all at the end of the report. In either case make the reference to them very clear. For example, you might refer to Fig. 1 provided that the appropriate drawing is clearly labeled Figure 1.


You should keep a bound notebook in which you record in ink all your data, descriptions of your activities, and diagrams of your apparatus. Clearly date every entry. Record any parameter or occurrence that could possibly influence results. A common unacceptable practice is jotting down data on a scrap of paper and copying it into the notebook later. Do not erase or use liquid paper; mark through errors or deletions in such a way that they can still be seen. This notebook should also contain outlines of what you plan to do and dated comments about what you have done. Include very clear sketches of all equipment arrangements. Jot down ideas you have for improving the experiment even if it isn't practical to do them at the time. Leave a few blank pages at the front for a table of contents.

Special Projects

In addition to several standard experiments, you are encouraged to do a special project which has not been done before at MSU. The special project may count up to half of your experimental requirement. You should decide on and plan your special project before February 3. On that date turn in a brief proposal for you experiment including specifications for any specialized equipment or supplies that you will need. In some cases equipment must be ordered. You will do the lab work at the end of the semester.

You may get ideas for special projects anywhere. To help those of you who don't already have definite ideas I can suggest articles in American Journal of Physics and Scientific American which contain interesting possibilities.

Important Rules

  1. Never work alone except with special permission.
  2. Return tools to toolbox and lock it before leaving lab.
  3. Leave the lab and equipment in better condition than you find them. Never return broken equipment to the shelf. Make minor repairs yourself. Notify me of problems you can't fix. Make sure equipment is properly put away after you are finished with it; if you are not sure where it goes, ask.
  4. Make equipment work! Often, students complain about equipment which doesn't work. One of the most valuable things you can learn in this lab is how to locate problems with equipment and solve them. In physics research, things often don't work right and, even when they do work right, appear not to have.
  5. Do background reading on every experiment before you begin it. Put in your notebook a brief plan of attack.
  6. Before you perform any operation, be prepared to give a detailed answer to this question "Why are you doing that"?

Standard Experiments

You are being supplied with a partially complete lab manual that describes experiments that have been done in this course in previous semesters. Below is a list of those experiments along with a rough estimate of the number of weeks of lab that will be required to finish each. I will base actual time credit on my observations of your work. You are expected to perform at least 10 weeks-worth. Before beginning an experiment, discuss it with me, so that I may guide you toward the proper equipment and make suggestions. Before beginning experimental work prepare a plan of attack and let me comment on it.

Topics Covered

  1. Determination of G from the Cavendish Balance
  2. The Ratio of CP to CV for Gases
  3. Millikan Oil Drop Experiment
  4. Bainbridge Tube Measurement of e/m
  5. Obtaining Planck's Constant from Measurements on a Light bulb
  6. Franck-Hertz Experiment
  7. Lifetime of a Metastable State
  8. Determination of the Speed of Light from a Rotating Mirror
  9. Modulated-Laser Measurement of the Speed of Light
  10. Microwave Optics
  11. Michelson Interferometer
  12. Index of Refraction of Gases
  13. Holography
  14. Grating Spectrograph
  15. Grating Monochromator
  16. Absorption Spectroscopy
  17. Fluorescence Measurements
  18. Interference with Polarized Light
  19. Investigations of Stress Birefringence
  20. Polarization Changes Produced by Internal Reflection of Light
  21. Polarization Effects in Internal-Mirror He-Ne Lasers
  22. Faraday Effect in a Solid or Liquid
  23. Raman Effect in a Liquid
  24. Flash-Lamp-Pumped Dye Laser
  25. Fraunhofer and Fresnel Diffraction
  26. Rutherford Scattering
  27. Nuclear Spectroscopy