Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-L] circuit analysis : a simpler approach?



I have found this discussion to be very interesting from a pedagogical point
of view. I do agree with JD that Kirchhoff's laws are dispensable in most
practical circuits. Actually I think that having students use them in the
intro course is very bad pedagogy.

Kirchhoff's laws basically allow circuit analysis with absolutely no
understanding of circuits. This is similar to many of the procedures that
students are taught to blindly follow. Students can figure out how to
analyze a fairly complex network by breaking it down into simpler
combinations. By being pushed to figure out some of these methods in an
inquiry fashion, students will not only have much greater understanding, but
they will become better problem solvers.

Do these laws have a place in physics pedagogy? I would say they do, but
not in the same sequence or the for the same reasons. As conceptual
constructs they should be understood. They can also be introduced as what
to do, when you can not be clever by breaking down the circuits into smaller
pieces. As such they can be de-emphasized and placed very late in the
teaching. Once you have analyzed a circuit, they could also be used to run
some checks on the validity of the analysis.

Klaws are a reasonable example of using simultaneous equations, so if you
want to get students to do this piece of mathematics, that might be a good
usage. This is definitely not a good goal for the intro courses because you
want students to "understand" the conservation relationships. Most intro
students will not be using complex math at all. Indeed they will not be
using physics at all, but building good habits of thinking and higher level
thinking can be applied to other endeavors.

The example given by JD of generalizing conventionsl parallel, series
circuits using complex notation is OK for the physics/EE major, but
inaccesible to the intro students. But intro students would not be
encountering such circuits in their physics course. Many examples of Klaw
problems are actually very artificial rather than being actual circuits.

John M. Clement
Houston, TX