Re: Ohm's Laws
- From: Hatunen <hatunen@xxxxxxx>
- Date: Wed, 07 Nov 2007 09:28:48 -0700
On Wed, 7 Nov 2007 12:23:49 +0100, "Igor \(t4a\)"
<merfert@xxxxxxxxxxxxxxxxxxx> wrote:
Again, the impracticability of achieving a constant-current
source is emphasized by considering what happens to the
voltage across the output as the load impedance is increased
toward an open circuit. it approaches infinity. So a true
constant-current source implies an infinite voltage source
with an infinite source resistance.
The impracticability of achieving a constant-voltage
source is emphasized by considering what happens to the
current at the output as the load impedance is decreased
toward a short circuit. It approaches infinity. So a true
constant-voltage source implies an infinite current source
with a zero source resistance.
This is what we call a model.
Practically, mains circuits are considered constant voltage. It
is, of course, impossible to have a *true* constant voltage
source. And you are explaining why mains circuits have fuses or
breakers.
--
************* DAVE HATUNEN (hatunen@xxxxxxx) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *
.
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