Physics Experiments To Inspire Undergraduates? 249
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 (Score:5, Interesting)
Gas turbine engine. (Score:4, Interesting)
Build a gas turbine engine out of an old turbocharger.
Or if you want to go all out, have them fire up a GE90-115B. ;-)
Theremin (Score:2, Interesting)
Water "Bottle" Rockets (Score:5, Interesting)
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.
Muon Lifetime (Score:4, Interesting)
Ripple tanks (Score:3, Interesting)
When I was in High School (in 1964!) we had a physics curriculum called PSSC. If you can find an original textbook it is full of ideas. It was largely an experimental approach, which was perfect for me at the time. The most fun I had was building a ripple tank. You could add high-tech challenges like digital control of the wave generators (I suggest 2 for point source and 1 for line waves)to look at effects of phase variation and interactions of different wavelengths.
Standing Wave... of Fire! (Score:5, Interesting)
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.
Some ideas... (Score:5, Interesting)
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...)
Re:Coil Guns (Score:5, Interesting)
I had one idea last fourth of July to separate di-hydrogen-monoxide with some electrodes into a floating pillar of its component parts hydrogen and oxygen, then reassembling it very quickly.
I saw another guy install a switch in a baseball bat, and connect it to a camera. Then use it to take pictures at very interesting moments. On the watermelon, on the egg, , on the soda can.
Another idea might be some kind of musical instrument. Put a microphone next to almost anything that vibrates or beats and it can make interesting musical noise. You can investigate variations in length, density, etc, and how that varies the tone and pitch.
Maybe build a trebuchet?
I still say let 'em blow something up.
Trebuchet (Score:3, Interesting)
There was plenty to build and measure, but there is a ton to calibrate which is the important part. In order to see how far we were from the ideal launch many of us (on our own) were calculating the theoretical maximum lanch distance using the weight we had loaded, the weight of our "ammo" (a tennis ball) the length of the arm and attached string, and quite a few more factors.
The best part about this is you have a very wide variety of math you can accompany with it because a lot of the more negligable forces can be ignored or simplified. If you want you can just do some basic angular momentum / vector acceleration equations and get pretty close to the correct efficiency or you can go as in-depth as calculating frictional forces, properly describe the launch cord motion as a differential equation, etc.
Honestly the experience was probably the most inspirational experience I had not just in physics class, but in school. I'd compare it to a good episode of mythbusters because not only did we get to build something cool and do some calculations, but we got to launch things across our school's front lawn.
Interferometers, Astronomy, Books and Web Sites (Score:5, Interesting)
Here's a simplified Michelson-Morley interferometer experiment
http://tonic.physics.sunysb.edu/~dteaney/F07_modern/lectures/mlab1_michelson.pdf [sunysb.edu]
http://en.wikipedia.org/wiki/Michelson-Morley_experiment [wikipedia.org]
http://www.wikinfo.org/index.php/Michelson-Morley_experiment [wikinfo.org]
How about building your own Radio Telescope
http://www.radiotelescopebuilder.com/ [radioteles...uilder.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 [gettysburg.edu]
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 [about.com]
http://www.educypedia.be/education/physicsexperiments.htm [educypedia.be]
Re:Standing Wave... of Fire! (Score:3, Interesting)
Holy crap, that's awesome. It's absolutely simple enough for a first year undergrad, and it involves fun with fire, so it'll certainly inspire some of them. Sadly, I'd never even heard of this thing until you mentioned it. Though, now that I know it exists, I can't help but think a few bands I know may be getting a suggestion for their live shows...
Bubble Fusion (Score:2, Interesting)
http://www.absoluteastronomy.com/topics/Bubble_fusion
For students it is be exciting to be apart of the human quest for fusion power. And is useful as a teaching tool for all methods of fusion. Taking part in a controversial research project can be very stimulating.
The experiment can be attempted using a pyrex 100mL flask and placed piezoelectric speakers at key locations. The flask is filled with deuterated acetone and the speakers are modulated at different frequencies until cavitation and sonoluminescence is achieved. Their are several types of neutron detectors that can be used. Some of them cheaper than others but less sensitive.
Anyways, just an idea. Alternatively, you can also build a fusor, which is a bit more involved but with the right setup could also work for a short term project, would require you todo some pre-building. http://www.fusor.net/ [fusor.net]
-alot cheaper than ITER or Lawrence Livermore laser confinement...
Lumen meter? (Score:3, Interesting)
Have them build a lumen meter for measuring light bulbs. Its the sort of thing that each year and add to or redesign since it seems simple to get initial results but the problems go much deeper.
Give topics, let them come up with the spec. (Score:2, Interesting)
To engage them, give them broad topics to explore such as conservation of momentum, change of state, magnetism, and illustrate them with they own experiments.
That microgravity on human body thing's good too.
The TeslaTire (Score:1, Interesting)
Magnetic Tires - "the concept of an internal electromagnetic system within a radial tire with applications including but not limited to: use as a braking mechanism; potential replacement of mechanical engines and hence elimination of reliance on fossil fuels; and regeneration of electrical energy from induced current to dynamically recharge the batteryâ
Isaac Lim
isaac.lim@me.com
Frickin' Lasers (Score:5, Interesting)
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.
Re:Coil Guns (Score:3, Interesting)
Anything that blows up is probably a Chemistry experiment, not a Physics experiment. Electrolytic decomposition of water into hydrogen and oxygen is a chemistry experiment.
The only thing like that I can truly put in the category of Physics is the "Ice Bomb" experiment, which is extremely hazardous. Somewhere on the internet, through some professional Physics & Chemistry website, I saw the best video of that experiment ever. They got a cast iron sphere about 2 inches thick and about 4 inches in diameter, it had an huge cap with threads about an inch deep. They filled it with water and sealed it up, it was truly a 4 inch cannonball with solid iron walls 2 inches thick in all directions. Then they dropped it into a big vat of slushy water ice and dry ice. All that was surrounded by piles of sandbags and plexiglass shields. After a few minutes, the ice bomb exploded, flinging shrapnel everywhere, ripping apart the sandbags and the protective plexiglass shields. They retrieved the pieces of the metal sphere, it was ripped into pieces. Wow you should have seen that explosion.
Nowadays, people do this experiment with pop bottles, it's lame. Find a good Physics supplies shop that is focused on educational demonstrations, they have loads of great gear for doing experiments like this. You can't beat the classic demonstrations, although it may be expensive to arrange the really good equipment (especially if you're going to destroy it).
Build Steel Pans (Score:2, Interesting)
Build an ECG meter (Score:2, Interesting)
fusor (Score:1, Interesting)
I'd like to suggest building "the world's simplest fusion reactor. Go to fusor.net and read Tom Ligon's article on it. A vacuum chamber with pump and a medium voltage transformer are the only spendy items involved, and I'd think an undergraduate physics lab might already have access to such things. Tom's write-up implies that 72 man-hours should be more than sufficient to build the thing and start to play with it.
It's not quite as awesome as burning or exploding things, but creating nuclear fusion has to be pretty cool.
Kelvin Water Dropper (Score:1, Interesting)
Generate thousands of volts and make sparks from dripping water.
http://en.wikipedia.org/wiki/Kelvin_water_dropper
I made one of these as a physics project, and they do work.
I used:
rubber tubing
glass tubing heated and stretched in a Bunsen burner flame to make the nozzles
small tin cans with the bottoms removed for the rings through which the water dripped
the tin lids in the bottom of large polythene beakers as contacts
insulated wire soldered to cross-couple the lids and cans
retort stands with dry polythene bags as insulation to hold the tin cans
After a minute or two of operation the fine water drip/spray breaks up into very fine droplets which then curve upwards as they pass through the tin cans. You can then get a 5-10mm spark between two bare patches of the cross-coupling wires.
Shape Memory Alloys (Score:1, Interesting)
Big G (Score:1, Interesting)
Try and measure Big G (the Gravitational Constant) by a torsion balance. I've seen it done during a lecture at university - the rotation of the balance was measured by reflecting a laser off a mirror mounted on the balance.
It's exceptionally hard to be accurate, and the whole experiment can be unduly affected by a crowd of people walking into a lecture theatre at the start....
More actual experiments: (Score:1, Interesting)
sorry if those came up before, did not want to read through all the nonsense comments:
Millikan's experiment, measure charge of an elektron
Speed of light using Michaelsons turning mirror method. Requires a mirror, an electric drill, a collimator mirror, a laser and a scope (great fun to build).
make holograms (no calculations, still fun)
pauli traps (careful, high voltage)
Experimental errors (Score:3, Interesting)
They were given the task of measuring the earth's magnetic field, and estimating altitude/height of the buildings around the campus based on it.
Of course what they weren't told was that the physics lab has an Nuclear magnetic resonance lab, with
Catches out the lazy undergrads, or the ones that 'fudge' results, whilst rewarding those that are paying attention and going to the effort to explain quite why the physics lab gives such insane results.
Build a Michelson Interferometer (Score:2, Interesting)
Leidenfrost (Score:1, Interesting)
Leidenfrost effect ( http://en.wikipedia.org/wiki/Leidenfrost_effect ) . You can measure lifetime of water drops as a function of the temperature of the surface they are being droped on.
You can measure the same effect on liquid nitrogen by immersing a metal piece on liquid nitrogen and measure temperature of the piece as a function of time (I did it with a diode put inside a sealed hole on the metal piece).
They can identify different heat transport regimes.
Both of the experiments are really nice to see. And it's always fun to work with liquid nitrogen.
Re:Some ideas... (Score:3, Interesting)
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)
You don't need ultrasonic or transducer. Two cheap microphones and the correct connector to get them on separate channels and a computer is plenty. Make a loud sound and record it with each microphone. Find the distance from microphones to the sound source. The find the time shift of your signal between the right and left channel. Divide the two and you have the speed of sound. There are a lot of variations you can make, but the basics are easy to do.