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Physics 42 Projects and Photos
Contents
Introduction
Physics 42 is intended to teach physics deeply. It is also intended
to be fun!
When designing a course of study that requires a lot of very
difficult work, intended to stimulate the imagination, it seems very
reasonable to include at least one component that is freeform,
relatively unstructured, and which is as available to the least capable
student in the class as to the best and most capable.
For these reasons, it has long been my tradition to offer an "extra
credit project" opportunity as a standard component of any introductory
course. This project is typically worth 1/3 (or more) of a letter grade
and is my version of "honors physics" (our department doesn't have a
formal honors program at this level). A student that does a project who
doesn't totally blow off the course, especially attending class
and doing their homework, cannot fail the course as an "F" is promoted
to a "D" by the project. A student doing poorly (but trying their best
otherwise) who does a project that would have gotten a "D" gets instead
a "C-".
This grade promotion is offered outside the usual curve (as
in, I first determine the grades from a histogram, statistics, and
experience and then promote those grades as indicated by any projects
that are completed), as the work is beyond my standard
expectations for the course.
Students who choose to do a project often look back on it as one of
the high points of their class experience. As well they should! Some
of the projects students have tackled in the past have been truly
spectacular! Many projects (especially those completed sufficiently
before the end of the semester) effectively double promote the
student -- the project itself requires a student to learn a block
of physics far, far better than mere classroom study permits, and this
is reflected in significantly higher exam scores and hence a higher
baseline grade before promotion.
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Projects from Spring, 2003
| Project Title |
Description |
Students |
| Electrostatic Motor |
Attempt (unsuccessful) to run electrostatic motor on atmospheric
electrostatic energy. Electrostatic motor itself successful, though. |
David Hsu, Nadine Oosmanally, Michael Ruth |
| Tesla Coil |
Wildly successful Mad Science project, created lightning! See
pictures below. |
John Barton, Daniel Seifer |
| Crystal Radio |
Homemade "crystal" radio (used a diode). Didn't work in my
office but they never do (too much steel in the walls). Good first
effort. |
Joyce Coppock |
| Crystal Radio |
Storebought "crystal" radio (used a diode, prewrapped
inductance). Didn't work in my office ditto. Gave Peter all my
leftover kits to see if he could combine them into one that works. |
Peter Blair |
| Homemade Speaker |
Speaker made out of (no kidding!) a yogurt cup, a pie plate, a
strong permanent magnet, and a homemade coil. It worked! Stevie Nicks
out of a yogurt cup, whoda thunk it...next step, will it work as a
microphone run backwards? |
Ingrid Kaldre |
Photos
Tesla Coil, ready to operate.
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The tesla coil on its rolling cart and ready to operate. Note the
row of capacitors on the bottom shelf, the spark gap (the PVC pipe
section on the fan on the bottom shelf), the primary (thick copper
tubing), secondary (LOTS of turns), and doughnut on top (where all the
sparks come out. The big supply transformer is visible (barely) on the
second shelf -- the upright grounded post on the top shelf to the left
of the secondary is to ground any overlong arcs so they do NOT arc back
to the primary, which would be, um, "bad" for the supply transformer,
the supply wiring, and everything electrical plugged into the supply
transformer's circuit.
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Tesla Coil.
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The tesla coil in operation at night, when the streams of charge are
highly visible. These streams are roughly 0.5 meters long. Note the
weak discharge on the wire to the doughnut.
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Tesla Coil.
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The same, a slightly better picture. I need practice holding still
for night photographs...
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Tesla Coil.
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Arcing over to the protection (grounded) pole one gets a creditable
imitation of lightning. Note the brightness of the sustained arc. A
PVC section has been removed from under the doughnut, bringing it
closer to the pole so the arc can establish.
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Tesla Coil.
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A CD bites the dust. The energy in the arcs is sufficient to
blow/burn the foil right off of the CD. Contrary to popular belief,
Tesla coils are moderately dangerous and can cause all sorts of damage
from simple blown electrical equipment to fires and severe burns.
Anyone considering a tesla coil project should read about the
dangers first.
While demonstrating some years ago how a tesla coil lights up a
fluorescent tube from a distance (hardly necessary, as every overhead
light in the room -- all turned off -- was flickering) I got the tube
too close to the secondary and drew a momentary arc that cheerfully went
through the glass of the tube like it wasn't there, and through me to
ground. It was not fun, although fortunately it was too short a
hit to do any real damage. (My students don't seem to mind that I drool
occassionally while lecturing.) I was lucky (and stupid) -- a hit from
the primary can easily kill.Be Careful!
Note also the corona surrounding the insulated supply line
between coil and cap/CD. Remember, there is no such thing as an
"insulator" against enough voltage, and the voltages present range from
the 110 V line cord (dangerous, but insulable) to perhaps 15 kV at the
primary (very dangerous, not very insulable) to around a 1 MV on the
doughnut (very dangerous, not insulable, but fortunately high frequency
which slightly reduces the danger -- see link above).
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Tesla Coil.
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The CD gets still more punishment. Note the arc brightening up as
the CD shortens the doughnut's path to ground relative to the similar
picture above.
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Resources
- Tesla Coils are
Dangerous!
- You must read this before even thinking of building a
high-voltage-primary tesla coil as a class project. Tesla coils must
not be operated in the building, near a car (filled with
explosive gasoline), within a couple of meters of a human, and you have
to convince me that you're not going to be careless or clumsy near high
voltage electricity before proceeding.
- Physics 42 Lecture
Note Template (tarball)
- for anyone seeking to create a set of lecture notes as an extra
credit project. The rules for such a project: a) Get the chapter
approved. Wimpy chapters, like 1,2, or 12 are not ok. b) The notes
should include at least four example problems drawn from the material,
worked out as you would present them in class. It is ok for one or two
to come out of the text, but one or two should be "original". c) DO all
the required derivations in your notes. In class I do the derivations
at the board, but I know how. You're PREPARING to be able to do the
same thing, and the first step is to do the derivation completely in
your notes, so you've done it recently. You can always then refer to
your notes if you get lost trying it in a class. d) Evidence of 12-16
hours total work. Figures are great (any postscript figure can be
included as shown in the template). Back when I used notes, I needed
some 8-12 pages of notes (pretty widely spaced notes as in the template)
to fill an hour lecture. Use this to guestimate what is required to
cover a chapter.
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to help spread the word so others can find it as well.
Note, Robert G. Brown is generally either rgb or rgbatduke on many external
sites crosslinked here.