| |
 |
|
|
Science Forum Index » Physics - Research Forum » details of what is happening with A/C electricity
Page 1 of 1
|
| Author |
Message |
| snowlynx@gmail.com |
 Posted: Tue Mar 06, 2007 1:58 pm |
|
|
|
Guest
|
I understand that A/C creates power like a water hose alternating
pressure back and forth. I also see that the power plants' ground/
neutral is the other half of the supply which gets moved back and
forth.
1. How can I understand the physical actions of electrons and energy
by comparing the A/C alternating sine wave and the idea of water/
energy flowing back and forth from a "hot" line and a "neutral" line?
Jacques |
|
|
| Back to top |
|
| Eckard Blumschein |
| Posted: Wed Mar 07, 2007 5:11 pm |
|
|
|
Guest
|
On 3/7/2007 12:58 AM, snowlynx@gmail.com wrote:
Quote: I understand that A/C creates power like a water hose alternating
pressure back and forth. I also see that the power plants' ground/
neutral is the other half of the supply which gets moved back and
forth.
1. How can I understand the physical actions of electrons and energy
by comparing the A/C alternating sine wave and the idea of water/
energy flowing back and forth from a "hot" line and a "neutral" line?
Jacques
While your question does nor have to do with research, I hope for not
just telling to you possible mistakes but recall to the research
community general pitfalls which might affect current research.
The potential of electric ground is analog to ambient pressure.
You imagines the electric conductor like a water hose with electrons
instead of water moving in it back and forth. Analogies are always a bit
risky. In this case the analogy is perfect if you restrict to stationary
pressure corresponding to voltage. However, in case of the electric
system, kinetic energy is not located inside the conductor but
attributed to the magnetic field surrounding it. In particular, the
magnetic field can be bundeled within a ferromagnetic core. You might
expect the kinetic/magnetic energy to be found within this core. Wrong
once again: It is largely located in a tiny gap of this core.
As a corollary I recommend: Be as careful as you can. As long as you are
a learner you have to grasp theory. If you intend to be a researcher, do
not take anything for granted what evades measurement, not even future
time,
cf. Wikipedia: Time in physics->why time causes paradoxes in physics.
Eckard Blumschein |
|
|
| Back to top |
|
| paulaireilly |
| Posted: Wed Mar 07, 2007 5:11 pm |
|
|
|
Guest
|
On Mar 6, 6:58 pm, "snowl...@gmail.com" <snowl...@gmail.com> wrote:
Quote: I understand that A/C creates power like a water hose alternating
pressure back and forth. I also see that the power plants' ground/
neutral is the other half of the supply which gets moved back and
forth.
1. How can I understand the physical actions of electrons and energy
by comparing the A/C alternating sine wave and the idea of water/
energy flowing back and forth from a "hot" line and a "neutral" line?
Jacques
It is a little tricky, because electrons create their own fields, so
analogies with water driven by more-or-less constant gravity fields
fail at times. However, in this case, we can look at a pretty good
analogy. Consider a pipe driven by a pump at one end with a resevoir
at the other end:
PUMP ========================================= RESEVOIR
The pump raises the pressure to higher than the ambient pressure in
the resevoir and drives water to the right. Then it alternates and
lowers the pressure to lower than the ambient pressure in the
resevoir. Water sloshes back and forth in the pipe. You must think
of the movement of the water as much slower than the speed of sound,
so that there are no shock waves and everything is quasi-equilbrium
(Poiseulle flow - there can be viscosity, but no turbulence) This is
because in electrical circuits, the flow speed is typically a billion
times slower than the schockwave speed (millimeters per second vs
speed of sound in an electron gas = many kilometers per second.)
[ Mod. note: Poiseuille would be the correct spelling. -ik ]
The pump acts like your variable voltage source and the resevoir acts
quite a bit like your ground wire, something with a very large
capacitance and some dissipation. Just as the water pressure of a
pipe plugged into a resevoir tends to equalize with the pressure of
the resevoir by water flowing in or out, so does the voltage in a
circuit plugged into "ground" tend to equalize with "ground"
voltage.
You could put gravel or stuff cotton in the pipe, and it would impede
the flow of water and dissipate energy as heat (like a resistor). You
could put turbines in and draw energy out of the oscillating water
flow to do mechanical work. (Analogous to motors). You could put
switches and multiple pipes in, even run a fluid computer.
If you try to think of capacitors and inductors, the analogies start
to break down, but very roughly, something like water towers act like
capacitors, and momentum of water acts a bit like inductance, but the
analogy is very shaky here and I wouldn't pursue it too far. The
energy in an inductor isn't in the kinetic energy of the electrons
(well, a neglible amount is) but in the magnetic fields that the
motion of the charge carriers create, and it's difficult to make a
fluid analogy for that. |
|
|
| Back to top |
|
| bz |
| Posted: Sat Mar 17, 2007 2:32 am |
|
|
|
Guest
|
paulaireilly <paulaireilly@gmail.com> wrote in news:1173233930.410368.318220
@j27g2000cwj.googlegroups.com:
Quote: If you try to think of capacitors and inductors, the analogies start
to break down, but very roughly, something like water towers act like
capacitors, and momentum of water acts a bit like inductance,
A chamber with a flexable diaphram blocking 'through flow' while
allowing pulses to pass is an analogy for a capacitor.
The water tower or a 'water hammer suppressor' like device is an
inductor.
--
bz
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
bz+spr@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap |
|
|
| Back to top |
|
| Aaron Denney |
| Posted: Tue Mar 20, 2007 3:36 am |
|
|
|
Guest
|
On 2007-03-17, bz <bz+spr@ch100-5.chem.lsu.edu> wrote:
Quote: paulaireilly <paulaireilly@gmail.com> wrote in news:1173233930.410368.318220
@j27g2000cwj.googlegroups.com:
If you try to think of capacitors and inductors, the analogies start
to break down, but very roughly, something like water towers act like
capacitors, and momentum of water acts a bit like inductance,
A chamber with a flexable diaphram blocking 'through flow' while
allowing pulses to pass is an analogy for a capacitor.
The water tower or a 'water hammer suppressor' like device is an
inductor.
A water hammer suppressor could act like an inductor in certain
regimes, but I don't see how a water tower would do that. As you say,
an in-line capacitor would be a chamber with a diaphragm. A water
tower, even with two pipes connected, doesn't act like that, but as a
capacitor tied to ground.
i.e. not as (A) ---||--- (B) but as
(A)
|
|
+---||---+
| |
| V
(B)
Hmm. I bet you could hook up a turbine to a flywheel to get a decent
intuition about inductors.
--
Aaron Denney
-><- |
|
|
| Back to top |
|
| robert bristow-johnson |
| Posted: Wed Mar 21, 2007 5:10 am |
|
|
|
Guest
|
On Mar 17, 8:32 am, bz <bz+...@ch100-5.chem.lsu.edu> wrote:
Quote: paulaireilly <paulairei...@gmail.com> wrote in news:1173233930.410368.318220
@j27g2000cwj.googlegroups.com:
If you try to think of capacitors and inductors, the analogies start
to break down, but very roughly, something like water towers act like
capacitors, and momentum of water acts a bit like inductance,
A chamber with a flexable diaphram blocking 'through flow' while
allowing pulses to pass is an analogy for a capacitor.
The water tower or a 'water hammer suppressor' like device is an
inductor.
i don't think so. i would say that water towers are the hydrological
analog of a DC battery. the (dual ported) chamber with a flexible
diaphramis a good analog of a capacitor (or one with a spring loaded
piston). probably the only analog of an inductor that i can think of
is a chamber filled with fan-blades or propellors that are all
connected to flywheels. the momentum of the flywheels will resist
changes in the current flow as what happens in inductors. a pipe with
obstructions (screens, gravel, etc) that causes turbulence would be a
the hydrological analog of a resistor. a diode would be modeled as a
pipe with a "check valve" (one-way valve), a transistor or amplifier
would be modeled with more difficulty.
r b-j |
|
|
| Back to top |
|
| bz |
| Posted: Wed Mar 28, 2007 8:00 am |
|
|
|
Guest
|
"robert bristow-johnson" <rbj@audioimagination.com> wrote in
news:1174353923.551452.230800@e1g2000hsg.googlegroups.com:
Quote: On Mar 17, 8:32 am, bz <bz+...@ch100-5.chem.lsu.edu> wrote:
paulaireilly <paulairei...@gmail.com> wrote in
news:1173233930.410368.318220 @j27g2000cwj.googlegroups.com:
If you try to think of capacitors and inductors, the analogies start
to break down, but very roughly, something like water towers act like
capacitors, and momentum of water acts a bit like inductance,
A chamber with a flexable diaphram blocking 'through flow' while
allowing pulses to pass is an analogy for a capacitor.
The water tower or a 'water hammer suppressor' like device is an
inductor.
i don't think so. i would say that water towers are the hydrological
analog of a DC battery. the (dual ported) chamber with a flexible
diaphramis a good analog of a capacitor (or one with a spring loaded
piston). probably the only analog of an inductor that i can think of
is a chamber filled with fan-blades or propellors that are all
connected to flywheels. the momentum of the flywheels will resist
changes in the current flow as what happens in inductors. a pipe with
obstructions (screens, gravel, etc) that causes turbulence would be a
the hydrological analog of a resistor. a diode would be modeled as a
pipe with a "check valve" (one-way valve), a transistor or amplifier
would be modeled with more difficulty.
Transistors are actually easy to model as fluidic amplifiers.
http://en.wikipedia.org/wiki/Fluidics
--
bz 73 de N5BZ k
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap |
|
|
| Back to top |
|
| |
|
Page 1 of 1
All times are GMT - 5 Hours
The time now is Thu Dec 04, 2008 9:19 pm
|
|