UTModPhy: Experiments: The Party Line

What do you want from the course?

What do you want from this course? Some good answers to that question include,

I want straighforward experiments that demonstrate the material covered in class. This class is pretty hard as it is, so I want well-defined labs that cover basic, straightforward topics.

That actually covers most of the labs we do! Try one of the following:

Electron Diffraction	Hydrogen-Deuterium	Atomic Spectroscopy
Photoelectric Effect	Blackbody Radiation	Franck-Hertz
Relativity	Solar Spectroscopy	Nuclear Spectroscopy

I want to be confronted with the central mysteries of Modern Physics. When my garbageman asks me how we know that light is quantized, I want to be able to tell him all about the photoelectric effect. Shock me into belief.

Good. Almost every lab we do has a classical prediction which is refuted quite strongly by the results; these ones demonstrate the most notable or significant enigmas. (P.S. If you are doing/have done one of these labs, and don't see what the fundamental mystery is, ask your TA!)

Electron Diffraction	Franck-Hertz	Ramsauer-Townsend
Chaotic Dynamics	Relativity	Photoelectric effect
Superconductivity

I want to encounter and develop physical intution about advanced topics. When I meet a topic, I like to have a physical model to motivate the blackboard scribbling. Even if this means I have to do some extra reading, I learn best in the lab.

There are many important topics which seem quite minor or disconnected on first encounter. This is a great opportunity to build the correct mental models and motivate their study, even if that is not for one or two years hence.

LED: Determination of h	Chaotic Dynamics	Ramsauer-Townsend
Semiconductor Physics	Superconductivity	Fun with a laser
Electron Spin Resonance	X-ray diffraction

I want exposure to advanced laboratory methods and equipment. Toys! I want toys! Big fancy toys, so that I can get an undergraduate research project or a summer job.

We are rapidly improving this area of the course, although this goal is covered quite well in senior lab. As far as toys go, you can play with lock-in detectors, advanced nuclear counting equipment, and more. You also have many opportunities to learn the basics of data acquisition, a skill that can make you quite attractive to an employer. Finally, although none of the labs require a computational (simulation) component, if you are interested and highly motivated it's possible we can recommend something appropriate.

Superconductivity	Electron Spin Resonance	Fun with a laser
Any LabView lab; currently these are
LED: Determination of h	Relativity	Ramsauer-Townsend
Superconductivity

I want to learn to write polished, lucid technical reports with clean prose and intelligent presentation of information.

You'd better have this as a goal, because you will have to meet it for every lab you do. :-) In many ways, this is the most important goal; if you leave the course with a fuzzy notion of the Bohr model and a powerful grasp of technical writing, the world is a better place.

The TAs review the experiments
Flip's Review	Windell's Review
Atomic Spectra	AS
Basic, straightforward lab. You will spend three full days taking data. Put some thought into finding a good algorithm for taking the data; with the right routine, the data taking will go quickly. Once you figure out the right way to treat it, the analysis is easy. Similar in technique to H2-D2; you should do either this lab or that one.	Physics in the dark, part I. Lots of knob turning, patience is required. Surprisingly accurate results are possible, and your data will look nice. Finding the unknown is fun if you like story problems (word problems).
Hydrogen-Deuterium Line Splitting	H2D2
Basic straightforward lab. You will spend three full days taking data. Put some thought into finding a good algorithm for taking the data; with the right routine, the data taking will go quickly. Once you figure out the right way to treat it, the analysis is easy. Similar in technique to H2-D2; you should do either this lab or that one.	Physics in the dark, part II. Apparatus is easy to use, but you should allow two days for data taking. It’s interesting, because you can do nuclear physics with light. The theory is more involved than for Atomic Spectroscopy, but analysis is easy. Similar in technique to Atomic Spectroscopy; you should do either this lab or that one.
Franck-Hertz	FH
This lab confronts you with one of the central mysteries of Quantum Mechanics. It clearly shows that atomic transitions are immediate, and that in-between energies really are forbidden. It’s easy to generate a lot of data… but then you get to analyze it all. I like the computer interface. It’s out of date but does its job well; be careful of the calibration, though.	Counterpoint: Yes, it’s a nice demonstration of the quantization of atomic energy levels, beyond the simple Bohr hydrogen atom. But… the apparatus is a little flaky. Occasionally, it is difficult to keep your signal levels from drifting and your signals may be hysterical (display hysteresis, that is). Analysis is straightforward. =)
Blackbody Spectrum	BB
This lab is great because you should be able analyze this experiment completely: you can understand and quantify (or at estimate well) all of the phenomena involved. You get to read books that are entirely devoted to tungsten and learn a lot of neat engineering details. (How they make that damn filament into a perfect coil, a tenth of a millimeter across…) That either excites you or it doesn’t. Also, you can’t beat an experiment that so clearly and richly demonstrates a fundamental physical law for under five bucks.	Hellooooo analysis hell. Ever wonder how a light bulb works? Well, now’s your chance, if you haven’t before. By the end of this lab, you will finally be able to explain the actually-pretty-interesting physics behind a simple household object to your {parents, brother, sister, dog, cat, lizard} .
LEDs and Solid State Physics	LED
A good chance to learn about the physics of diodes and semiconductors. The physics of the experiment is basic, but the physics behind that physics is huge. Strike the right balance. You may not do both this lab and the Photoelectric effect, since the goal of both experiments is the same.	You don’t have to do this lab in the dark, but you can if you want to. Data taking is a little tedious; take turns. Analysis is interesting and subtle. You will need to learn a little solid-state physics, but just a little. A good lab overall.
[Note: The "basic" physics underlying this experiment is described in your lab manual, in several technical papers, and in the experiment manual from the manufacturer. Unfortunately, we now have evidence to believe that it is, to some degree, hogwash. This means that students working this lab will get to help us develop the correct method. If you will be frustrated by an open-ended assignment, stay away.]
Photoelectric Effect	PE
Note: we redesigned this lab so ignore all the bad stuff you heard about it.
There is not a lot of analysis to do for this one. However, all that time you saved on analysis: you have to put it into understanding the circuits. You get to learn some basic electronics -- the op-amp follower circuit you use. It's stuff every physicist should know, and not enough to obscure the physics, which is both fundamental and straightforward.	This experiment includes a little work with electronics (operational amplifiers). Again, this lab has been redesigned for better or worse. In plain English, that means that you will be the guinea pig. You shouldn’t do both this lab and the LED Determination of h lab.
Ramsauer-Townsend	RT
When you meet scattering theory and the Schr�dinger equation, you have this experiment as a touchstone physical model, which is nice. This lab clearly demonstrates the wave nature of the electron, and your analysis can be quite rich. However, you have to learn some stuff not covered until QM II, which some people find frustrating (and others don’t). You get to play with Liquid Nitrogen. It’s easy to completely miss the peak you are supposed to see. Stop and think, "Where is this peak I am looking for?" Then look real carefully near there. (You can’t see the dip until you do your data analysis…)	Simple experiment, interesting physics. You get to see a genuine quantum-mechanical effect that defies classical explanation. The theory is a little more complicated than in other labs. You get to play with the leftover LN2, but we will not provide anything for you to freeze and break.
Solar Spectra	SS
This lab is really fun, but you don’t get to see that much sun. A little, though. It can be hard to find good data on the Fraunhofer lines. If you haven’t done H2D2, get a friend or the TA to show you how to use the plotter. If you’re going to finish this lab in one day (you can and you should) you need to know how to use the plotter. It will be helpful if you have someone do a sun dance on the roof of RLM.	This is the only experiment (short of the solar group project) in which you will be able to see sunlight during lab hours. (Sign up now!) Data will only take one (sunny) day to collect. It will be helpful if someone in your group has performed the H2D2 experiment. This lab covers both atomic spectroscopy and blackbody radiation topics, and analysis is simple. You should not do this lab if you did the solar group project.
X-Ray Diffraction	X
I’ve had students love this lab, explore the theory deeply and learn a broad range of topics from physics and chemistry. It really clears up the theory of crystallography which you may or may not have learned from electron diffraction. You get to do an experiment with one-part-in-ten-thousand accuracy. It’s also open ended: you have a lot of choice about what to include on your theory section.	Not exactly a hands-on experiment. My students last semester didn’t like it very much. On the bright side, you will get some exposure to modern crystallographic techniques. And, if you’re lucky, modern X-rays.
Nuke Spec	NK
Radiation sources are a serious matter, and should be taken seriously. However, in case you are worried about handling radiation sources, let me note that these sources are so weak we don’t even have to fill out a safety form to get them. When you consider the normal paranoia associated with any safety issue, that should put it in perspective. I also recommend Relativity for anybody the least bit motivated.	Expose yourself to radiation! Seriously, radiation (and not much of it) is the only thing that you have to fear about this lab. Calibration takes a little work, but the equipment is rock-solid. Do relativity instead, if you’re looking for interesting physics.
Relativity Superconductivity	RE SC
These labs (and ESR) are fairly new; we believe that they are ready to be done by the world at large, so you don’t have to be hard-core to try them. These labs cover advanced topics and are open-ended, however, and were developed by groups that took extra time and basically built the experiment. So it’s still a possibility to extend and improve the experiment if you’re interested.
Electron Spin Resonance	ESR
This lab covers an advanced topic – spin – that you will not really cover until your second QM class. When you do meet it, though, it is easy to miss the physical forest for the mathematical trees. This experiment will have you witness it first hand, and give you a foundation on which to develop that intuition. This lab is still under development: only for the hard-core.	Not for the timid. There is an awful lot of stuff that you will have to do to get this experiment working. If you do, however, you will be justly rewarded—the physics here is great. A trio of gung-ho students rocked this one last semester. Will you be next?