Hi friends,

I have a question that has been bothering me and it's this:

Why won't current flow out of a single battery terminal to the ground if you connect it? By that I mean leaving one terminal floating and connecting the other.

Is it because inside the battery, the opposite charges are attracting the opposite charges and so they won't come out of a single terminal?

The question is because if you consider static charges, they will surely flow into the earth, but not with a battery.

Another question is, I have some difficulty with the fact that objects can have potential differences between themselves, but not with the earth. A battery again, has a potential diff between its terminals, but none with the earth, or other objects. Why?

And finally, Remember the zero at infinity that we consider when dealing with static fields? I want to know the relation between that zero, and the terminals of a battery, and how can I define the potential everywhere in space that is generated by the battery terminals? Even if it is zero everywhere, I am looking for a proof of this. Remember that a static charge +Q generates an electric field everywhere in space and there's a potential everywhere, and so there is also a potential difference between any two points in space, and a zero at infinity. So now is this situation the same as the battery? The battery afterall creates a potential diff between two points in space as well. So if I place a conductor in space, along a gradient of the field, the electrons will flow to one side of the conductor won't they ? So there will be a current, just it will soon stop, because the electrons aren't being moved back to the other end.


Can anyone please take the time to help me? Thanks a lot!

 

The prime rule of electricity is that you can't continually move charges without a return path.
So battery current flow out of one terminal with the other open since there's no return path.

the fact that objects can have potential differences between themselves, but not with the earth. A battery again, has a potential diff between its terminals, but none with the earth, or other objects. Why?

Why not?
The potential difference of a battery is between it's terminals but the total battery charge is neutral with respect to "earth" so this is no potential difference.

how can I define the potential everywhere in space that is generated by the battery terminals?

The potential in space is determined by the battery voltage between its two terminals which generates the corresponding electric field in space between the two terminals.

So if I place a conductor in space, along a gradient of the field, the electrons will flow to one side of the conductor won't they ? So there will be a current, just it will soon stop, because the electrons aren't being moved back to the other end.

Is that a problem?

 

If you consider the battery as a point then yes it's charge is neutral with respect to the earth, but the fact is that the terminals are at a distance from each other and so one of them will be closer to the earth unless you set them at exactly the same distance and so there will be a difference between the electric field strengths caused by each terminal to the earth. And this also seem to apply for the zero at infinity....... I find this confusing.


If you are going to answer my question with "is that a problem?", then you might as well just not say anything.

 

'Zero potential at infinity' is a definition not a measurement. If we need to measure the battery potential difference then we need a test charge (voltmeter current). We move this test charge with the meter circuit using energy (easily with low conductance wires to the measurement circuit ) and use the generated potential (voltage) between test points of the meter. Moving a test charge from one isolated battery terminal to some ground reference on the moon or the earth if the battery is floating in space also requires energy but here we don't have an easy path for the test charge to move. Batteries are not capacitors. The voltage of a battery is from a electrochemical process that usually involves a huge number of bound ion charges and low voltages that result in a large equivalent capacitance.

 

nsaspook, you answer provides some interesting insight, but I can't make much of it because your wording of it confused me.

You say that a voltmeter provides a test charge in order to measure the potential different between the terminals. I think that is a fascinating insight, but it made my confusion worse because why does the meter need to provide its current, why doesn't it just use the measured circuit current instead? You are saying the meter provides it own current to measure the voltage. This is 100% confusing. If the meter is providing its own current then it has a voltage source inside it to provide this current, and so how does sit measure the outside voltage and not its own?

All I'm asking here is why won't charge flow from battery +ve to the earth since it has loads of +ve charge at the +ve terminal? Shouldn't the charge just flow out ? Secondly, I need to know why the zero at infinity definition doesn't make sense for a battery? I want to know this in terms of path integrals

 

nsaspook, you answer provides some interesting insight, but I can't make much of it because your wording of it confused me.

You say that a voltmeter provides a test charge in order to measure the potential different between the terminals. I think that is a fascinating insight, but it made my confusion worse because why does the meter need to provide its current, why doesn't it just use the measured circuit current instead? You are saying the meter provides it own current to measure the voltage. This is 100% confusing. If the meter is providing its own current then it has a voltage source inside it to provide this current, and so how does sit measure the outside voltage and not its own?

All I'm asking here is why won't charge flow from battery +ve to the earth since it has loads of +ve charge at the +ve terminal? Shouldn't the charge just flow out ? Secondly, I need to know why the zero at infinity definition doesn't make sense for a battery? I want to know this in terms of path integrals

The test charge is the free charges of the measurement probes that are connected between the battery terminals. When connected we have a circuit for current flow that uses a small amount of electric potential energy from the battery in the measurement circuit to give us the electric potential difference as a measurement. Infinite resistance is equal to an open circuit, an open circuit is the same as a isolated charge with no test charge to extract energy for a measurement. When we think about the battery we don't see it as a isolated charged particle in space. The battery (and a normal electronics capacitor) is normally electrically neutral (fields cancel out outside the circuit elements inernal space) circuit element to some isolated distant point in space like the earth because its electrical field potential energy is concentrated between internal plates (Integ from infinity applies to radial fields from a point source) with charge separated by a chemical process not a static field from isolated point charge.

Is this PAULOCONSTANTINO?

 

A radial field is a field created by any charge. All charges are the same so you can work out any fields by using the individual radial fields.

The potential can also be defined by the energy required to bring +ve charges together. So in a battery, the voltage is the energy required to bring the charges together, divided by the total charge, so it's joules per coulomb, but note that this can also be defined by taking the integral from infinity to the battery for each charge in sequence, and that will give the same voltage.

 

Let us say you connect the negative terminal (surplus of electrons) of a 12V battery to ground.
Yes, electrons will flow from the negative terminal to ground, but only for a very short period of time (too short to measure).
The positive terminal will now be at +12V with respect to ground (which it wasn't before the connection was made).
This 12V electric field (positive potential attracts electrons) prevents more electrons from leaving the -ve terminal. Hence you don't end up draining the battery.

 

Sure it can be defined as such in a purely physics spherical capacitor context but we all know what it takes to make an actual measurement of the potential difference in a physical parallel-plate device.

Field lines diverging, field weakens with distance Field lines parallel, strength the same everywhere

 

If you are going to answer my question with "is that a problem?", then you might as well just not say anything.

Not saying anything.

 

MrChips: when you say "this +12V electric field prevents electrons from further leaving -ve", do you mean the internal battery electric field ? Which is what I offered as an answer to my own question. The +ve battery terminal has a lot of positive charge and this charge holds the electrons inside the battery. Is that what you mean buddy ?

 

Not saying anything.

 

Sure it can be defined as such in a purely physics spherical capacitor context but we all know what it takes to make an actual measurement of the potential difference in a physical parallel-plate device.

Field lines diverging, field weakens with distance Field lines parallel, strength the same everywhere

The field lines do weaken outside the capacitor. If you take the potential of a single plate, then an infinite plate would have infinite potential anywhere, and a physical finite plate has a weakening field outside. What I've been trying to do is to define everything as it's done in physics, in relation to infinity, because then I can make sense of any potentials. I find many concepts just too artificial and I find the point at infinity a perfect place to define everything relative to, because at infinity a positive charge has zero potential in relation to a field which points radially towards infinity.

I've had a few days of constant thinking trying to break through a lot of concepts and really make sense of them.

For example, the potential of a charged sphere. If you ask some people about this they will say you're talking non sense as "potentials are only potential differences", but clearly a charged sphere has a definite potential in relation to the zero at infinity. And so any potential differences can be taken as two positive potentials from infinity subtracted from each other.

This may seem strange to you guys but it's how I like to think.

Because some people will just say AHA, the potential between 2 cap plates is E*d, but this is only true approximately. I don't like to take things for granted like this.

 

This may seem strange to you guys but it's how I like to think.

A battery is not a single plate or a single point charge so trying to force a square peg into a round hole stops at the point of experiment. Measure the potential to earth ground of an isolated in space 9vdc battery + or - terminal with any multi-meter. Tell us what the voltage is between earth ground and that floating battery terminal.

 

What would you say the result would be, if you found the exact electric field produced by the terminals of a battery in space, as small as they would be outside the battery terminals. I tell you what I think it would be. They would be going from +ve to -ve yes, but outside the terminal they would start bending kind of like the outside of a capacitor, and the magnitude dropping to zero. If you now calculate the path integral from infinity to +ve, or -ve or another point in space, you will get a finite potential.

If anyone would like to prove me wrong I want to know

 

What would you say the result would be, if you found the exact electric field produced by the terminals of a battery in space, as small as they would be outside the battery terminals. I tell you what I think it would be. They would be going from +ve to -ve yes, but outside the terminal they would start bending kind of like the outside of a capacitor, and the magnitude dropping to zero. If you now calculate the path integral from infinity to +ve, or -ve or another point in space, you will get a finite potential.

If anyone would like to prove me wrong I want to know

Do the measurement and give us the results.

 

Do the measurement and give us the results.

Why are you being ironic. I never said this is relevant to engineering. This is physics and posted in the physics forum. If you want to be ironic and act like a retard then CONGRATULATIONS.

And it's me who gets banned in the end. Gotta love retards.

 

I have concluded that forums are space for idiots. I've only met rude, and retarded people here and other forums, who have no patience or desire to answer what they don't like, and treat others like shit.

I give back to you what you give me. Idiots. Fuckers. Retards.

Ban me as I'm never coming back to this shithole again.

 

A potential comes from separating charge. If you separate it from the carpet......it will return there. From the earth....it will return there. From a battery.....it will return there. From a Dam.....it will return there. It returns to the point of separation. Home.

A power supply does not supply charge.......it's only rotated by the potential.

This comment is in the electronic context. I'm not talking plasma physics.

 

I have concluded that forums are space for idiots. I've only met rude, and retarded people here and other forums, who have no patience or desire to answer what they don't like, and treat others like shit.

I give back to you what you give me. Idiots. Fuckers. Retards.

Ban me as I'm never coming back to this shithole again.

Will do. Bye.