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Things on the site itself that may be of interest to students or philosophers of any age or generation include complete online books of poetry, various support materials for the study of physics, and links related to beowulfery. All materials on this site that are authored by Robert G. Brown are Copyright 2004. The details of their Open Public License (modified) can be viewed here. If you use or enjoy anything at all on this site -- free textbooks, stories, programs, or other resources, consider hitting 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.


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Home Physics 41 Physics 42 Physics 53 Physics 53 (Summer) Physics 54 Physics 54 (Summer) Physics 55 (Summer)
Introductory Physics I Review Problems for Intro Physics I Introductory Physics II Equations du Jour (Old Intro Physics II) Review Problems for Intro Physics II Introductory Physics III Mathematics for Introductory Physics Classical Electrodynamics
Physics 319 Physics 231: Mathematical Methods for Physics Videos of Physics 53 Lectures One Page Calculus Review Identities for Electrodynamics Contact About

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
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Tesla Coil, ready to operate.

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.

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.

The same, a slightly better picture. I need practice holding still for night photographs...

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Tesla Coil.

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.

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.

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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Home Physics 41 Physics 42 Physics 53 Physics 53 (Summer) Physics 54 Physics 54 (Summer) Physics 55 (Summer)
Introductory Physics I Review Problems for Intro Physics I Introductory Physics II Equations du Jour (Old Intro Physics II) Review Problems for Intro Physics II Introductory Physics III Mathematics for Introductory Physics Classical Electrodynamics
Physics 319 Physics 231: Mathematical Methods for Physics Videos of Physics 53 Lectures One Page Calculus Review Identities for Electrodynamics Contact About

This page is maintained by Robert G. Brown, available at rgb at phy dot duke dot edu. This address is also associated with rgbatduke in e.g. stumbleupon or google code, in case you are looking.