If we connect a long wire to a battery, will battery produce more electrons?

WBahn

Joined Mar 31, 2012
29,979
I don't believe that electrons will leave the negative terminal of a battery until new electrons enter the positive terminal of the battery. Positive charges within the battery hold the negative charges inside the battery.

Connecting a long wire to one end of the battery does not, in any real sense, make a capacitor. No current will flow into the wire. Positive charges within the battery would prevent that from happening. The wire becomes a capacitor only when it is held close to the positive terminal. With this additional provision, there would be a small amount of current flowing for a short period of time.

I suggest that the original poster see A Kitchen Course in Electricity and Magnetism by David Nightingale and Christopher Spencer.
How close does the wire have to be before it suddenly becomes a capacitor? If it's moved just a little bit further away, why does it suddenly stop being a capacitor?

If our battery is 1.5V (I don't recall if the OP ever put forth a voltage), then even 1 aF (one attofarad, which is one one-millionth of a picofarad) capacitance would be enough to require ten electrons to charge it to that voltage. Just 0.1 pF would be enough to require a million electrons.

Now consider that two one-inch long pieces of 24 AWG wire separated by 6 cm (the height of a D cell battery) have more than 0.1 pF of capacitance between them.

Also, as previously described, if no charges are transferred to the wire, then you have a conducting wire that is in the presence of an electric field having a tangential component but without any resulting current flow.
 

BR-549

Joined Sep 22, 2013
4,928
Wbahn.......when you connect something to the positive terminal.......you change the whole setup.

When you add surface area to the positive pole........the battery will re-balance with a new charge amount for that new area.

Under normal conditions, you can not draw charge from a dipole source without referencing the other pole.

A monopole source is different because it has no reference that has to be balanced.

You can easily charge a wire with a monopole source, but only polarize a wire with a dipole source.

Does this make any sense to you?
 

WBahn

Joined Mar 31, 2012
29,979
Wbahn.......when you connect something to the positive terminal.......you change the whole setup.

When you add surface area to the positive pole........the battery will re-balance with a new charge amount for that new area.

Under normal conditions, you can not draw charge from a dipole source without referencing the other pole.

A monopole source is different because it has no reference that has to be balanced.

You can easily charge a wire with a monopole source, but only polarize a wire with a dipole source.

Does this make any sense to you?
No, because you are wrong. A simple example will prove it.

Imagine a capacitor constructed with a large circular plate as one terminal (let's call it the positive terminal) and a small circular plate (centered on the other) as the other (the negative terminal). There is also an annular ring that is the same outside diameter as the positive terminal and whose hole is barely larger than the negative terminal. This ring is in the same plane and centered on the negative terminal. You can imagine that we started with a negative terminal that was the same as the positive terminal and just cut a thin circle out of it to separate the two.

Now connect a battery between the two terminals (the annular ring is floating). You get a charge separation on the two terminals and a charge polarization on the ring.

Now connect a wire between the negative terminal and the annular ring. According to you there will be no flow of charge between the two, even though all we have done is extend one plate of the capacitor.
 

darrough

Joined Jan 18, 2015
86
How close does the wire have to be before it suddenly becomes a capacitor? If it's moved just a little bit further away, why does it suddenly stop being a capacitor?
The same point at which a diminishing lake becomes a puddle.

If a point must be defined, then take a good quality current meter. If it cannot detect any current, then the wire is not a capacitor.

What happened here is a clueless noob (Santa Claus) led you down a spurious path of inquiry. The only good response in such a situation is to quietly insist that the path he is headed down is spurious.

Suppose SantaClaus asked you for directions to a store, and you told him "go three blocks, turn left, and go another block", to which he replied "how many inches is three blocks". By entertaining his question, you are misleading the noob into thinking that it actually matters. The better course of action is to steer the noob off this path.
 
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WBahn

Joined Mar 31, 2012
29,979
The same point at which a diminishing lake becomes a puddle.

If a point must be defined, then take a good quality current meter. If it cannot detect any current, then the wire is not a capacitor.

What happened here is a clueless noob (Santa Claus) led you down a spurious path of inquiry. The only good response in such a situation is to quietly insist that the path he is headed down is spurious.

Suppose SantaClaus asked you for directions to a store, and you told him "go three blocks, turn left, and go another block", to which he replied "how many inches is three blocks". By entertaining his question, you are misleading the noob into thinking that it actually matters. The better course of action is to steer the noob off this path.
If that's your criteria, then as long as a single electron flows we have a current. Meters that are capable of detecting individual charge flow have been built. In fact, one of them works on just this principle -- a capacitance so small that the charge of a single electron results in enough voltage to prevent further flow. This electron is then gated off the capacitor and counted.
 

cmartinez

Joined Jan 17, 2007
8,220
If that's your criteria, then as long as a single electron flows we have a current. Meters that are capable of detecting individual charge flow have been built. In fact, one of them works on just this principle -- a capacitance so small that the charge of a single electron results in enough voltage to prevent further flow. This electron is then gated off the capacitor and counted.
Sort of quantum of charge... right?
 

WBahn

Joined Mar 31, 2012
29,979
Sort of quantum of charge... right?
Essentially, if I understand the context of the question. Of course, on the sub-atomic scale you have 1/3 and 2/3 electronic charges, so 1 electronic charge isn't technically the quantum of charge (if I remember my definitions correctly -- it's been a LONG time).

We routinely design ICs that do individual photon counting using capacitances in the femtofarad range and have to contend with parasitics that are measured in attofarads. Now, to be sure, photon counting is a LOT easier than electron counting.
 

cmartinez

Joined Jan 17, 2007
8,220
Essentially, if I understand the context of the question. Of course, on the sub-atomic scale you have 1/3 and 2/3 electronic charges, so 1 electronic charge isn't technically the quantum of charge (if I remember my definitions correctly -- it's been a LONG time).

We routinely design ICs that do individual photon counting using capacitances in the femtofarad range and have to contend with parasitics that are measured in attofarads. Now, to be sure, photon counting is a LOT easier than electron counting.
This quantum stuff is threading deep waters for me... but I find it fascinating, thanks.
 

WBahn

Joined Mar 31, 2012
29,979
This quantum stuff is threading deep waters for me... but I find it fascinating, thanks.
Me too. That single-electron current meter was something I read about in a NIST journal when I was an undergraduate working there nearly 30 years ago. I hadn't had a course in quantum physics at the time and so didn't even know what an achievement it was to do something on that scale -- but it was still pretty impressive.
 

BR-549

Joined Sep 22, 2013
4,928
WBahn......when I explain how a setup works......and you say I'm wrong...and
then you change the setup to prove I'm wrong.

I was explaining polarization......and you say no........and change the
circuit to a charge circuit.

You can not use my argument for the first setup......in your second setup.

Because I didn't explain the second setup. I explained the first.

Now, for your diagram.....the current flow in your diagram comes from
CHARGING the extended negative plate. This is because of SURFACE AREA and
CHARGE BALANCE from the positive plate.

When you put a capacitor across a battery....you do not increase battery's
capacity.......but you do decrease current response time. This is because
the capacitor plate can sink faster than the electrolyte.

A capacitor across a battery is like the shipping department of the factory.
It's the place where the prepared product waits to be shipped. This is also
the function of the terminal itself.

Polarization and charging are basic concepts. There is a difference.

How about this.

Back in my space battery setup........when we connect a 10 foot wire to
negative terminal, going westward.......the wire polarizes.....no charge
from negative pole to wire.

Now when we connect a 10 foot wire to positive terminal going
eastward..........you will get some flow in the wires now.......and you
think that the wires are charging like a capacitor............

But that is not what is happening.

What you did is change the surface area of the poles. The flow you see is to
equalize the charge to the new pole area.

These wires are not capacitor plates..........they are pole plates.

A capacitor is a passive polarizing device, a battery is an powered dipole
source.

That's a huge fundamental difference.

In the future......if your gonna change the setup..........please don't use my words or explanation on your new setup.
 

WBahn

Joined Mar 31, 2012
29,979
You are pretending that there is a difference merely because you choose to use different words for different things. But neither the battery nor anything connected to it knows what it is called by you or anyone else. Any two conductors that are (or can be) at different potentials form a capacitor. You can call them wires, capacitor plates, poles, or thingagigs. All they know is that if they experience a tangential component of an electric field anywhere within them or on their surface, a current will flow so as to cancel it out. If they are electrically connected to anything else, then that current may and usually will, at least in part, include flow to/from that something else.
 
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