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Before starting I have to put in a bunch of disclaimers:
- There's almost nothing new in this talk. You can find it all in Purcell's
book. I'd also like to thank Tom Moore for motivating me to try this approach
myself for the first time several years ago.
- Just because I recommend Purcell's approach doesn't mean I recommend
Purcell's book. I feel that the book itself is not suitable for an
introductory course, because many parts of it are too advanced and for a
variety of other reasons. To back up this opinion, I refer you to the ultimate
authority on the quality of textbooks, namely the reviews
on Amazon.com. Notice also that the price is now nearly a hundred dollars,
and that isn't going to improve student morale either.
- I'm not putting forward a complete curriculum for introductory
electromagnetism. The material that I'll discuss would occupy only about three
to five class sessions, and how you would teach the rest of electromagnetism
is up to you.
- I have, however, developed a 39-page text supplement that you could use in
a calculus-based introductory course. Click here to
download this document in pdf format (234K).
- I think that this approach should also work just fine in an algebra-based
course, with some loss of rigor because Gauss's law would be replaced by
intuitive arguments based on field lines.
- The prerequisites for this material are:
- Electrostatics (including either Gauss's law or some equivalent
statement about where field lines start and end);
- Familiarity with basic magnetic phenomena, like the fact that parallel
currents attract;
- Special relativity, specifically an acquaintance with the idea of
multiple reference frames, length contraction, and the fact that information
cannot be transmitted faster than the speed of light. (Students do not need
to know the full Lorentz transformation equations or anything about
relativistic dynamics.)
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