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



On 09/02/2015 01:57 PM, Lulai, Paul asked:

Is it better or worse to think of kirchoffs laws as conservation laws?
Loop rule as conservation of energy per charge.
Junction or node rule as conservation of charge.

Worse! Much worse!

I know there are a hundred textbooks out there that
«explain» things that way, but it's still not right.

In cases where Kirchhoff's «laws» don't work, energy is
still conserved and charge is still conserved.

If you imagine that KVL is a corollary of energy conservation,
when you go looking for violations you'll look in all the
wrong places. KVL fails miserably whenever there is some
curl in the electric field. A curly field still conserves
energy. Energy is no longer a single-valued function of
position, but it's still conserved.
Example: betatron.
Familiar example: ground loops.
et cetera.