academic politics and curriculum decisions: physics

[Gabe]

This is for anyone who has knowledge of electromagnetism and/or the university curriculum decision making process. I'd like only serious responses please, I am hoping to learn something here.

So, for those of you who have taken electromagnetism classes, you know the whole language, right. First you are taught the very basic process of electrostatics (charges, electric fields, definition of voltage). Then, one day, the teacher starts talking a whole different language. You learn about potential in a circuit, and about all the features in the artificial situations of idealized circuits. You learn that V=IR and kirchoffs rules.

Wait a minute though! What happened to the charges? What happened to the electric field. The mind checks for an understanding of mechanism, so you try to figure out what's actually happening with the charges in a circuit. I dare you to try it now. Try to explain some basic circuit phenomenon in terms of charges and electric fields.

If you've been taught electromagnetism the traditional way, you won't be able to do this. "how is there a potential difference in a wire across a circuit, when the source of the potential difference is all the way over there" "Does the electric field bend into the wire or something"?

The typical teacher responses to this are:

Robotically reemphasize that thier is a potential difference across the circuit.

Indroduce a vague (and false) principle of 'direct contact'

Say (falsely) that the electrons push each other along, like water in a pipe.

The truth is, in some very short time before the current flows, the electric from, say, a capacitor, pushes the charges around until they align in a 'steady state' distribution along the wire. Then there is actually an electric field in the wire and the current flows.

www4.ncsu.edu/~rwchabay/mi/circuit.pdf


So my real question is, why haven't physics professors changed thier way of teaching electromagnetism. The misconceptions the current method causes, and the lack of understanding it leaves students with is OBVIOUS.

So how do curriculum decisions get made, and what is preventing progress in curriculums in math and science departments?

[rhinosaur]

In the hard sciences, difficult concepts are sometimes (over)simplified to facilitate rapid, facile learning. Sometimes teachers and students will confuse what's written in the textbook with cold, objective truth. In reality, of course, the phenomenon is much more complicated, and would take too long to explain completely. I bet for each broad-brush-stroke paragraph in a textbook on electromagnetism, there are at least a hundred theses and "review" style books that explain the concept much more thoroughly.

Science is vast. Students need to understand the big concepts without being weighed down by the real complexity of the situation. As a result, all throughout undergrad, you're taught little white lies, and you gradually revise them and re-revise them until you're closer to the real truth. This is, in fact, pretty much how research works, as well. You encounter a phenomenon, do some tests (most won't work), make a theory, do some more tests (most won't work), and revise the theory, ad infinitum.

Of course, a good teacher would be able to answer your question correctly, but unfortunately, sometimes they don't know when to say "I don't know."

[ygolo]

I agree with the OP. There isn't a lot of connection between electrostatics and circuit theory.

Part of the reason is that the circuit theory (KCL,KVL, and its dervatives) is much more application driven, than electromagnetism.

I think, however, that teaching that charge redistribution facilitates eletric fields that lead to current flow is important, even if the details aren't worked out. That will make learning about the basic electronic devices much easier.