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In Reply to: RE: a hydraulic analogy posted by unclestu on July 05, 2015 at 22:17:48
You don't seem to understand how circuits, AC or DC, work.There has to be a complete circuit, AC or DC.
Power doesn't just fall out with no return path.
Let's think about the circuit between the output of a power amplifier and the speaker.
There is only AC flowing through the speaker wire.
There are two speaker wires so we have a complete AC circuit.
The current flows through the speaker wire and the voice coil in one direction causing the speaker cone to move toward you, then the current flows in the opposite direction causing the cone to move away from you.
Stu, think of it this way.........
AC is just DC that changes direction periodically.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 07/09/15 07/09/15Follow Ups:
Power applied to the speaker from the amp translates to work and heat Both of which do NOT return to the amplifier. One reason why we measure current in the forward vector and not the ground (at least for billing) because the energy consumed is dissipated (Not gone per laws of thermodynamcs)
If there is no work being done yes AC is alternating. But energy is being consumed in a fashion which can NOT be returned to the source.
"But energy is being consumed in a fashion which can NOT be returned to the source."Yes, a light blub puts out heat and light.
A speaker puts out sound and heat.
"If there is no work being done yes AC is alternating."
But a light bulb powered by AC is doing work.
A speaker doing work is powered by AC.
But, to get back to the original point, there is no direct current (DC) in a speaker wire or a IC cable, only current that alternates (AC) periodically according to the frequency of the music signal.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 07/09/15
It is obvious any work being done negates the possibility of being 100% alternating.
"It is obvious any work being done negates the possibility of being 100% alternating."
Stu, you can't just string a bunch of words together and hope that they make sense.
Tre' has already given several examples of work being done by alternating current. You can generate heat with AC or DC by passing current (AC or DC) through a resistor. How is the AC any different than DC? Mr. Ohm observed that a constant resistance in a circuit will drop the same voltage whether the current is alternating or direct. Isn't the current through a resistance "work" as you define it? Are you disputing Ohm's law?
I don't know why you keep saying that.
There's no DC driving an AC motor but yet the motor still spins and does work.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
key word is 100%. heat and work do NOT contribute to the return flow.
This is kind of an interesting paradox. Using the waterflow analogy, your statement makes sense. However, if you were to insert a resistor in the ground side of the circuit, and then if you were to measure the voltage drop across that resistor, you would find that the "current" (V divided by R) on the "ground" side is exactly the same as it is across the original load. This suggests that circuits are "the same", no matter where you place your measuring device, which suggests that there is no real difference between the ground side and the hot side, in terms of electron flow. Of course, another way to look at it would be to say that after adding the resistor, the "ground" side of the circuit consists of the connection between the newly installed resistor and the negative node of the circuit, but you can add an infinite number of resistors in series, and the current will always be the same.
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