Electricity basics

[rainfire]

Hi,

I am just wondering, since electicity always tries to return to the souce via the path of least resistance, what happens to it once it has returned to the source?

Is it just a case of all the electons loosing their charge?

Sorry if its a stupid question?

 

[cloche]

An electron can not lose its charge or it would become another subatomic particle !!!
Electric flow (= current) is something like an electron "displacement" along a conductor. What causes this is a potential difference (= voltage) between the two extremities of the conductor, i.e. an electron accumulation. Flow tries to eliminate this accumulation (= to zero the potential difference). That means that in order to sustain current along a conductor, the potential difference must be maintained "by something" (an elecro-chemical reaction for ex.), otherwise you get only an "instantaneous" discharge and nothing else.
Sorry for the extreme simplification, I'd rather suggest to read any high-school book about physics / electricity...

 

[IRstuff]

Consider what happens when you stop a fan; does the air go away?

TTFN

 

[electricpete]

Electric current usually flows in loops.

The [dc] electric source is roughly analogous to a pump in a closed loop piping system. The pump [source] provides the energy to keep the fluid (current) flowing around the loop.

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[jraef]

A good analogy is to string a row of coins in a stright line on the table, all with their edges touching. Flick the first coin, and the one at the end shoots off, yet all of the coins are still in their same relative position. The energy in the coin "movement" is analogous to electricity. So when electricity goes to "ground", technically there is still movement in the electrons, but now it spreads out so far over so many molecules, that the movement becomes insignificant if not indetectable.

Now think of those coins on a circular track. If you pick one and flick it, all of the coins will transfer that enegy in a circle back to the one you flicked, but only once per flick. As soon as you stop inputting energy to the circle, the coins stop transferring it from one to the other. A Generator or the chemical reaction in a battery is essentially a constantly flicking finger in that analogy. Energy is transferred in the circuit only as long as energy is put into it.

"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more."
Nikola Tesla

 

[vic3fan]

Quite often an analogy between the electric circuit and a pneumatic/hydraulic circuit has been made. The electric current flows in the electric conductors in the same manner as the air/liquid flows in the pipes and other components of that correspondent circuit.

Referring to the pneumatic/hydraulic circuit, we can easily imagine how the working fluid is collected into a tank and from here a pump pushes it back into the circuit.

I think that an electric source might do quite the same thing. The electrons might lose their kinetic energy, which is an external attribute; here the electric source may have its importance, to restore this type of energy. But the electrons don't lose their properties, such as their own spin rotation.

 

[IRstuff]

Part of your confusion arises from the concept of "source" of electrons. The "source" of electrons is the entire conductive path.

The voltage simply causes easily distracted electrons to move from one atom to another. It's exactly like musical chairs with matched electrons and chairs. When the music stops, all the electrons simply sit down.

TTFN

 

[alehman]

Think of a pump circulating water through turbine. As the water circulates, the turbine produces power. The water returns at the same flow rate it is pumped out, but at much lower pressure. The energy put in to driving the pump is consumed by the turbine.

jraef hit the nail on the head however - electrons don't really flow, they just cascade like a row of falling dominoes. That's where the water-in-a-pipe analogy fails.

 

[rbulsara]

As it is seen above, even experienced electrical engineers, inlcuding myself, find it very difficult to explain physics of flow of electricity in simplified terms, because it not as simple. In fact, it is not fully understood as to what exactly happens inside the material when electicity flows, but we all know its effects and how to manouver it in limited way to our benefit.

And to answer your basic question, IRstufff had the closest analogy, the electrons do not loose their charge, but they eventually settle down with a matching proton to have a net charge of zero in the end, just like the musical chair, except there is no shortage of a chair (as no one removed a proton from the conducting path), so no electron is left out.

Explanation of electricity lies in combination of wave propagation and some particle thoery and much more. Very similar to a body of water can move energy by moving mass (ike a pumped water or a river) as well as just the waves through it e.g. a tsunami in sea) or just pass on pressure differential as in case of a hydraulic press.

In fact in the end, electricity flows when there is a temporary pressure differentical between two points of a conductive path, just like as in hydraulics. If you remove the source of pressure difference, the work stops. The nature looks for evening out the pressure difference..be it electricity or anything else.

We can go on tangent on this..forever so I will stop.