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

[Diego Saravia <dsa@unsa.edu.ar>]

I think they are usefull to understand several aspect about modelling a
circuit, and every kind of system in wich you could view a network.

For example you must assign signs to forces and fluxes and understand the
meaning of a different sign in your solution, Understand conventions of
sources and sinks, and yes practice about formal schemas of reasoning. You
must follow strictly a method (without understanding or understanding the
reasons),.And then interpret the results.

If you have self capacitance abstraction you can put a condenser to earth
in your node and restore K law, you can understand about the real system
and the model.

etc.

There are interesting problems that you can visualize. For example if you
have a cutset of inductors, the usual set of equations  do not solve your
circuit. The K eqs results in a cero determinant. That is what I was asking
the other they, By the way thanks Prof. Denker for your very good answer, I
am still learning from that.

You can receive topological insignts and detect such cutsets and loops by
manipulating K eqs. In that cases you have stiff dif. eqs for example.

http://www.win.tue.nl/analysis/reports/rana05-37.pdf














2015-08-27 16:30 GMT-03:00 John Clement <clement@hal-pc.org>:

> 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
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@www.phys-l.org
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-- 
Diego Saravia
Diego.Saravia@gmail.com
NO FUNCIONA->dsa@unsa.edu.ar

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