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Physics Experiments To Inspire Undergraduates?
PShardlow writes "I have recently been asked to propose two projects for a 1st year undergraduate teaching laboratory in the summer term this year. These are projects that a pair of students will spend 36 hours working on, and as such can be quite in-depth. A good project would include something they can build, something they can measure, and something they can calculate. Previous projects have included cloud chambers, a Jacobs ladder, a laser Doppler speed camera, laser sound detection, smoke rings, and physical random number generators. This is an opportunity to really inspire students into the joy that can be experimental physics — but it only works if we demonstrators propose interesting projects. So I ask the Slashdot community for suggestions of fascinating projects to do, things that are relevant to today's physics problems but could feasibly be completed by a pair of first-year undergraduates in 72 man hours."
Coil Guns rock. Inspired me to get into electronics. One that shoots Fist sized slugs would be enough for any of us :)
This is not a viral sig. Copy it at your peril.
Accelerate small particles to high speeds, create mini black holes, destroy the planet. Quite fascinating IMO.
Perhaps a collection of "The Amateur Scientist" columns from Scientific American would be a good source of ideas? A CD of the columns has been published.
Securing time on the ISS might prove expensive so I have prepared this simulator out of a trampoline and high-speed camera. I'm not sure exactly what we're trying to prove here but rest assured, the undergrads will be inspired.
Kwisatz Haderach
Sell the spice to CHOAM
This Mahdi took Shaddam's Throne
In terms of physics experiments, I can't imagine something that would both capture the interest of the students, be cheap enough to have a school with a limited budget be able to afford, and allows for multiple variable parameters to be adjusted. It is also a great summer time project.
Yes, this is sending up a 2 liter plastic bottle (or whatever is handy) by filling it up with water and pressurizing it with compressed air to see how high it can go.
There are all kinds of things that you can measure and document, including thrust (including ISP if you want to get that technical), altitude, learning about trigonometry (to measure altitude), payload mass, and even learning about the basics of the laws of motion through a hands-on experiment. Knowing the altitude and how long it takes to fall from the apogee, you can also calculate the local acceleration factor due to gravity (which can vary from one place to another).
There are also a number of variables that can be adjusted in a controlled manner, such as water volume, air pressure, atmospheric conditions (do rockets fly higher in cooler weather vs. hot weather?), rocket shape, nozzle shape, and rocket size (2 liter vs. 1 liter bottles). You can observe conditions, develop formulas from experimental data, and make predictive theories for what happens when you adjust the variables.
For the really ambitious, there are some 2-stage rocket plans available if you dig up using search engines, but a simple rocket is comparatively easy to build. Be careful with the multi-stage rockets, as you can get enough altitude that you may need to file a flight plan with your local airport under experimental rocketry procedures.
Once upon a time I did a lab were we used a very simple scintillator and an old photomultiplier tube to detect muons and estimate their lifetime. If you have the parts (including the electronics), it is fun. Exciting? Well depends on the student.
One of the projects I got to work in my first year of undergrad was a flaming standing wave generator. While Jacob's ladders and Theremins are cool, you can't actually *see* what's going on... not so with the flaming standing wave!
The actual name is the Ruben Tube (not be confused with a Rubix Cube), and it's a fairly simple design, too. Just a hollow tube with holes along the top. One side has a hard cap with a place to attach a gas tube, as with a Bunsen burner. The other side has flexible cap, with a speaker pointing at it.
Turn on the gas, light the tube, and play a constant frequency over the speaker. It sets up a standing, longitudinal wave in the tube, which means compressed and sparse areas of the gas. This lets the students see the wave in the flames, and makes it look like the much-easier-to-visualize transverse wave.
It's easy, it's cool, it's visual, and it helps students wrap their minds around an important aspect of physics. All in all, a great experiment.
Here are a doublet of papers for an undergraduate laboratory demonstrating Bell's Inequality and and entangled photons. The whole apparatus (detailed in the second paper) is estimated to cost USD 15k circa 2002, so the optical elements have probably come down in price since then.
1. Entangled photons, nonlocality, and Bell inequalities in the undergraduate laboratory. [American Journal of Physics 70, 903 (2002)], Dietrich Dehlinger, MW Mitchell. http://arxiv.org/abs/quant-ph/0205171/
2. Entangled photon apparatus for the undergraduate laboratory. [American Journal of Physics 70, 898 (2002)], Dietrich Dehlinger, MW Mitchell. http://arxiv.org/abs/quant-ph/0205172/
i\hbar\dot{\psi}=\hat{H}\psi
Ultrasonic tape measure / speed of sound experiment. Ultrasonic transducers are easy to come by; students should send some pulses out one, and then sense the return pulse, giving either a numeric indicator or a voltage level that corresponds to the delay time. A little electronics heavy, but if they have had a background in electronics it should be pretty fun. Proof of concept: ultrasonic tape measures at Home Depot for $15. (Trick: you have to build some kind of ultrasonic horn to channel the pulse and collect the return pulse -- otherwise it diffuses too much)
Lunar range finder. Get a green laser pointer and modulate it with a digital stream. Mount a beamsplitter on a little telescope and point it at one of the Apollo landing sites. Send the laser pointer beam out the telescope, pick up the return signal with a photodiode at the eyepiece. With digital correlation, you can measure the distance to the Moon in only a few minutes of integration. This may be a little ambitious for a 36 hour project, but it makes a dandy six-week independent project. As a side bonus, have them calculate the strength of the return signal. It turns out that the experiment wouldn't work without the retroreflectors planted there by the astronauts.
Million-volt van de graaf generator. Given a length of acrylic tubing, a long rubber band, a couple of brushes, a motor, and a big metal ball you too can make sparks that leap halfway across the room. If you really do get a megavolt, you can put a Geiger counter nearby and look for gamma rays(!)
Barometer. Make a barometer that can measure the height of your building. Pretty simple to do - just requires mercury, a glass tube, and care, or (for a more sensitive one, but harder to calibrate) an columnn of vacuum oil with a sealed partial vacuum at the top - but very moving: you can demonstrate the mass of air with remarkably simple equipment.
Pipe organ. Have them cut the tubes to length to create a scale.
Spectroscope. Stanford used to give out posters that could be folded up to make a little spectroscope, with a $0.10 transmission grating slide as a dispersive element. I handed them out to my CU students and asked them to do "something interesting" with them. One of them taped over the slit. Another one used razor blades and sketched the Fraunhofer spectrum of the Sun. Yet another used it to debug a sputtering apparatus for his work/study job. You probably don't want to be that open-ended, but you can certainly ask them to make one and calibrate it using fluorescent lights. Everyone but tape-boy really felt inspired by actually *seeing* spectral absorption and emission lines.
Doppler radar. Not as hard as it once was, this may still be on the ambitious side. Edmund Scientific has microwave transmitters that will serve. Heterodyne the signal with the return pulses, the output frequency gives you the speed.
Measure the curvature of the Earth using a car's odometer and a sextant. Cheap but effective can be had for $25-$30 at sailing supply stores. Have the students travel about 60-100 miles north or south and measure the altitude of a celestial object at both places at the same time of day. Students can "shoot the Sun" at true noon on successive days (compensating for the analemma) or "shoot Polaris" on successive nights at the same time. (Even Polaris is about a degree off the pole, so you can't shoot Polaris at different times on the same night without compensating for that...)
I've always found it frustrating that so many projects described as "experiments" aren't experiments - they're (optionally cool) projects replicating somebody else's work, but you're not learning anything new, you're just validating what somebody else already learned. That can still be fun - hands-on experience is different than book learning for most people, and blowing things up is always a good time - but it's not an experiment.
I've seen lots of freshman engineering / design projects that are at least not just replication - building bridges with toothpicks, making eggs survive dropping from high windows, etc., but even those are often not done with actual science in the process, just empirical engineering.
Some of the typical blowing-things-up projects can also be experimental - make your potato cannon, figure out something about the amount of energy you're getting from the fuel and how far the potato goes and therefore conclude something about your gun's efficiency. (You already knew you needed to point it at a 45 degree angle for maximum distance, and probably even why...) Can you find other ways to learn something new from your projects, even if it's less interesting that the fun of doing the project?
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Here's a simplified Michelson-Morley interferometer experiment
http://tonic.physics.sunysb.edu/~dteaney/F07_modern/lectures/mlab1_michelson.pdf
http://en.wikipedia.org/wiki/Michelson-Morley_experiment
http://www.wikinfo.org/index.php/Michelson-Morley_experiment
How about building your own Radio Telescope
http://www.radiotelescopebuilder.com/
For that matter you could get them to build their own Dobsonian although the physics there isn't too hard (basic optics), especially if you don't hand figure the mirror. There's also a large metalwork or woodwork component that might not be considered relevant.
Here are some really good astronomy tutorials (though the prac work is done with simulated software). You might be able to modify them to something more practical
http://www3.gettysburg.edu/~marschal/clea/CLEAhome.html
Some of the topics covered by the above
Radio Astronomy of Pulsars
Astrometry of Asteroids
The Revolution of the Moons of Jupiter
The Rotation of Mercury by The Doppler Effect
Photoelectric Photometry of the Pleiades
Spectral Classification of Stars
The Hubble RedShift-Distance Relation
The Flow of Energy Out of the Sun
The Quest for Object X
Jupiter's Moons and the Speed of Light: The Classic Roemer Experiment
There are books and web pages out there....many tend to be geared to highschool, then there are some that would require you to up your insurance...so you'll have to sift through them
http://physics.about.com/od/physicsexperiments/tp/experimentbooks.htm
http://www.educypedia.be/education/physicsexperiments.htm
These posts express my own personal views, not those of my employer
What the hell is this with the lasers? These are not projects that are comprehensible on a fundamental physics level, at least not in the construction of the projects you described. And Jacob's Ladder? Seriously? I remember doing that experiment in JUNIOR HIGH school. What has happened to science education today?
I'll give you an example of a laser experiment gone wrong. I remember when I was a junior in high school back in the 1970s, I was taking AP Physics, and lasers were brand new and expensive. But our school just bought one and we were dying to figure out experiments to fiddle with it. One day I read an offhand remark in a physics book that the angle of polarization of a laser beam could be altered by a magnetic field. This seemed impossible to me, sure a laser was an electromagnetic phenomenon, but it was light, how could magnetism affect it? So I figured I could get one of our strongest magnets that weighed about a hundred pounds, run the laser through the gap, and measure deflection with a couple of simple polarizing filters. But no matter what I did, I could not measure any deflection. The teacher suggested I try using a longer beam, maybe hundreds of yards between the source polarizer and the detector. That was a total red herring. My lab partner and I tried all sorts of things to use as long a laser path as possible, a few hundred yards even, but even a car driving by the building would make the whole rig vibrate enough to make it impossible to hit the target, let alone measure the polarization. After a week of fiddling around, we finally went back to the physics teacher and admitted defeat. The teacher burst out laughing, and said, "oh of course, what you were trying to do is impossible, and the length of the beam is irrelevant. It would take massive magnets the size of a house to cause any measurable deflection. I just wanted to see what lengths you'd go to to try to measure it." Oh was I pissed.
Well anyway, I have a dim view of the sort of example physics experiments you described (other than the cloud chamber). We did much tougher experiments in high school. Try giving your students the classics, experiments they'll really learn the FUNDAMENTALS of physics from. I have fond memories of doing the Miliken Oil Drop Experiment in high school, it was so much fun I did it over and over to get more accurate results. Or give your students old school equipment like oscilloscopes. You little kiddies DO know what an oscilloscope is, don't you? We did experiments like setting up two microwave emitters side by side to generate an interference pattern, then hooking up an oscilloscope to a detector, then moved the detector around to measure the high and low energy points of the pattern, then plotted the positions of the detector over graph paper. The teacher didn't tell us the frequency of the emitters so we had to work that out for ourselves from the interference pattern. There are loads of classic physics experiments using oscilloscopes, but they are largely forgotten today because the teachers never learned to use them properly when they were undergrads. Maybe it's time for YOU to learn about them.
If you can't get freshmen physics students motivated by the classic experiments showing the most fundamental aspects of physics, experiments that once were so difficult that they were only done in the greatest labs of Nobel Prizewinning physicists, but now are easily performed in any school lab, you will fail as a physics teacher, and at the goal of teaching physics. Flashy gadgets with frickin' lasers are no substitute for the beauty of the simplest physical phenomenon. If you can't get students to see that through your labs, it will be your failure, not theirs.