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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 :)
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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.
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.
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...)