electricity, metal and magnetism

[DyerWolf]

Is it possible to generate an electric current without generating any magnetic field?

I know that a changing electric current passing through a wire generates a magnetic field. Is there any chance that this is due to our use of metals?

Could a non-metallic conductor not create the magnetic field?

[papageno]

Is it possible to generate an electric current without generating any magnetic field?

I know that a changing electric current passing through a wire generates a magnetic field. Is there any chance that this is due to our use of metals?

Any flow of charge produces a magnetic field (see Maxwell's equations).

Could a non-metallic conductor not create the magnetic field?

Currents in non-metallic-like conductors occur mostly by hopping: the electrons tunnel from site to site without "flowing" through the material.
The amount of charge transferred this way is several orders of magnitude smaller than for conductors, but a steady current should produce a magnetic field anyway.

[Pinemarten]

AC current in 'twisted pairs' create two magnetic fields that cancel each other.

[papageno]

AC current in 'twisted pairs' create two magnetic fields that cancel each other.

Yes, of course.
But I didn't think that that was the point of the question.

[JohnD]

DW,
"Is it possible to generate an electric current without generating any magnetic field?"

Is a battery a too-simplistic answer?
Or lightning?

John

[tusenfem]

DW,
"Is it possible to generate an electric current without generating any magnetic field?"

Is a battery a too-simplistic answer?
Or lightning?

John

A battery stores "electricity" and does not create a magnetic field unless you let current flow.
Lightning will most definitely create mangetic disturbances.

[Pinemarten]

I seriously doubt it, although someone on the site may use the apples/oranges button on their calculator to figure it out.
All current produces a field, just as all masses have gravity. There is no field if there is no 'flow'. A battery has no field, with no load. AC current doesn't exist without a load, and thus no flow.
The field only happens with the movement of electrons.

[Pinemarten]

Is it possible to generate an electric current without generating any magnetic field?

I know that a changing electric current passing through a wire generates a magnetic field. Is there any chance that this is due to our use of metals?

Could a non-metallic conductor not create the magnetic field?

I must have misunderstood the bold.
Twisted pairs were specifically designed to generate electricity without the side-effects of the magnetic field.

http://en.wikipedia.org/wiki/Twisted-pair

[Len Moran]

I must have misunderstood the bold.
Twisted pairs were specifically designed to generate electricity without the side-effects of the magnetic field.

http://en.wikipedia.org/wiki/Twisted-pair

Twisted pairs provide a means of reducing significantly interference inducing electrical currents in the circuits connecting a source to a detector from being amplified. It only works if the twisted pair forms a balanced circuit and couples into a differential amplifier. Since the induced currents will be in the same phase, the differential amplifier gives an output of zero in a perfectly balanced system. Obviously any error in the balance will manifest itself in terms of some percentage output being produced as a result of the interference.

A twisted pair would cancel out a magnetic field only if the phase of the generated fields were opposed to each other. If you fed into each circuit strand currents of opposite phase, this would result in the field cancelling out. (Or in the case of direct currents, currents of opposite polarity.) Is this what you meant?

[Pinemarten]

Twisted pairs provide a means of reducing significantly interference inducing electrical currents in the circuits connecting a source to a detector from being amplified. It only works if the twisted pair forms a balanced circuit and couples into a differential amplifier. Since the induced currents will be in the same phase, the differential amplifier gives an output of zero in a perfectly balanced system. Obviously any error in the balance will manifest itself in terms of some percentage output being produced as a result of the interference.

A twisted pair would cancel out a magnetic field only if the phase of the generated fields were opposed to each other. If you fed into each circuit strand currents of opposite phase, this would result in the field cancelling out. (Or in the case of direct currents, currents of opposite polarity.) Is this what you meant?

Yes.

[JohnD]

My misunderstanding too.
No, a current implies a field - Maxwell's Laws and all that.
And in your car you may have carbon conductors to the spark plugs. The current through those certainly produces a field!

John

[rebel]

Hey guys,

At work today I noticed coolant in a bucket under my machine and the coolant (a water/oil mixture) was rotating just like the magnetic lines of flux from a magnet. I noticed also that the auger motor was on, directly above it, causing the coolant to rotate in these two directions. The coolant rotated just like the invisible lines of flux, one clockwise and the other counter clockwise. When the motor was turned off the water stopped moving, and when turned on it did it again. Does this mean that water or a solution of water can be magnetized?

I figured this would be a good spot for this because your talking about electricity and magnetism!

[tusenfem]

Hey guys,

At work today I noticed coolant in a bucket under my machine and the coolant (a water/oil mixture) was rotating just like the magnetic lines of flux from a magnet. I noticed also that the auger motor was on, directly above it, causing the coolant to rotate in these two directions. The coolant rotated just like the invisible lines of flux, one clockwise and the other counter clockwise. When the motor was turned off the water stopped moving, and when turned on it did it again. Does this mean that water or a solution of water can be magnetized?

I figured this would be a good spot for this because your talking about electricity and magnetism!

MMM I don't totally understand the whole descrioption but anywho...

A mixture of oil and water (don't mix very well), there will be, most likely, be some metallic particles in the oil that can interact with a magnetic field.
You say you have a auger motor above it. Being not really up to date with that motor I assume it is driven electrically and there will be a magnet or something that acts as a magnet. This can, naturally, if the fluid is close enough, drag the metallic particles along. I don't see how you get the two directions, unless there are two "motors" that are creating oppositely rotating magnetic fields.

In the end it comes to, if you have metallic particles in a solution you can use a magnetic field to set them in motion.

[01101001]

Does this mean that water or a solution of water can be magnetized?

Water is naturally diamagnetic. It is repelled by a strong magnetic field, observably repelled by a strong one.

My favorite demo of that is to take a good-sized rare-earth neodymium magnet and immerse it in water so it is barely covered. If you look at the reflection of the supposed flat water above the magnet, you'll notice it is slightly disrupted, as extra water is piled up there.

(Oh, I just looked for a Web image of the diamagnetic water illustration described above, and found a nice page on seeing the effect. They even play with oil-and-water mixtures: Wondermagnet.com experiments.)

How strong was the motor and how close was it to the water?

Still, without an analysis of what was in the bucket, you should consider the presence of magnetic materials with the water.

[EDG]

This a related question:

What actually is electricity? One of the ATM threads (Tusenfem knows the one ) got me wondering - I'd always assumed it was literally the flow of electrons from one place to another. But wikipedia at least claims that:

Electricity [...] is a general term for the variety of phenomena resulting from the presence and flow of electric charge.

So does that mean that if you bombard something with charged ions (whether they're positively or negatively charged) or even protons (which are + charged) then electricity is flowing? So it's not just electrons? Is the solar wind "electricity"?

I can imagine a lightning bolt being "electrical", or "electricity", but it seems wrong to me that a moving through a field of charged particles is "electricity".

I'm possibly overthinking this .

[swansont]

This a related question:

What actually is electricity? One of the ATM threads (Tusenfem knows the one ) got me wondering - I'd always assumed it was literally the flow of electrons from one place to another. But wikipedia at least claims that:



So does that mean that if you bombard something with charged ions (whether they're positively or negatively charged) or even protons (which are + charged) then electricity is flowing? So it's not just electrons? Is the solar wind "electricity"?

I can imagine a lightning bolt being "electrical", or "electricity", but it seems wrong to me that a moving through a field of charged particles is "electricity".

I'm possibly overthinking this .

Ions movings in a solution give you current.

[jlhredshift]

What if we turn the question around and ask, if we have a magnetic field, do we have electricity?

[hhEb09'1]

but it seems wrong to me that a moving through a field of charged particles is "electricity".

You seem to have left off the a " ", but special relativity may be relevant, I'm not sure

What if we turn the question around and ask, if we have a magnetic field, do we have electricity?

Do you mean, an area of space that has a magnetic field within it? Is there electricity in it too? Do you mean an electric field, or the movement of charged particles? Obviously, if there are no particles in the area...

[jlhredshift]

You seem to have left off the a " ", but special relativity may be relevant, I'm not sure Do you mean, an area of space that has a magnetic field within it? Is there electricity in it too? Do you mean an electric field, or the movement of charged particles? Obviously, if there are no particles in the area...

Not that complex, I was thinking a bar magnet. From what little I know it has to do with the "spin" of the electron. Having built and used solenoids it always amazed me how much DC current it took to equal the holding power of a bar magnet.

[tusenfem]

Okay, I think that we are dealing here a not well-defined problem. The question from EDG_ is "what is electricity" and according to my Concise Science Dictionary it is defined as:

Any effects resulting from the existence of stationary or moving electric charges.

basically the same that EDG_ wrote from Wiki. However, in physics things that happen are "electrical" (or mechanical) but hardly any physicist will say electricity, as from all-day-life this term has become synonymous with electrical current (there is no electricity so the tv does not work). Therefore, we use more detailed names as electrical current or electrical charge. (I even saw a billboard with Dame Edna saying "the change is electric", advertising an electric rasor). So, I think that the problem is that "hard core" physicist do not use the term electricity in their lingo but use more detailed descriptions, whereas outsiders consider most of these things to be electricity.

So, I guess I would say everything that has to do with charges is "electricity" at least according to the definition, but then this electricity has certain subfolders:
(very crude)
- charges in rest: electrical charge density
- opposite charges moving in the same direction: bulk plasma flow (hey what happened to the "electrical" here?)
- opposite charges moving in opposite directions: electrical current
- etc. etc.

Just my 2 cents, before I leave for the day.

[tusenfem]

Okay, I think that we are dealing here a not well-defined problem. The question from EDG_ is "what is electricity" and according to my Concise Science Dictionary it is defined as:

Any effects resulting from the existence of stationary or moving electric charges.

basically the same that EDG_ wrote from Wiki. However, in physics things that happen are "electrical" (or mechanical) but hardly any physicist will say electricity, as from all-day-life this term has become synonymous with electrical current (there is no electricity so the tv does not work). Therefore, we use more detailed names as electrical current or electrical charge. (I even saw a billboard with Dame Edna saying "the change is electric", advertising an electric rasor). So, I think that the problem is that "hard core" physicist do not use the term electricity in their lingo but use more detailed descriptions, whereas outsiders consider most of these things to be electricity.

So, I guess I would say everything that has to do with charges is "electricity" at least according to the definition, but then this electricity has certain subfolders:
(very crude)
- charges in rest: electrical charge density
- opposite charges moving in the same direction: bulk plasma flow (hey what happened to the "electrical" here?)
- opposite charges moving in opposite directions: electrical current
- etc. etc.

Just my 2 cents, before I leave for the day.

[korjik]

Okay, I think that we are dealing here a not well-defined problem. The question from EDG_ is "what is electricity" and according to my Concise Science Dictionary it is defined as:



basically the same that EDG_ wrote from Wiki. However, in physics things that happen are "electrical" (or mechanical) but hardly any physicist will say electricity, as from all-day-life this term has become synonymous with electrical current (there is no electricity so the tv does not work). Therefore, we use more detailed names as electrical current or electrical charge. (I even saw a billboard with Dame Edna saying "the change is electric", advertising an electric rasor). So, I think that the problem is that "hard core" physicist do not use the term electricity in their lingo but use more detailed descriptions, whereas outsiders consider most of these things to be electricity.

So, I guess I would say everything that has to do with charges is "electricity" at least according to the definition, but then this electricity has certain subfolders:
(very crude)
- charges in rest: electrical charge density
- opposite charges moving in the same direction: bulk plasma flow (hey what happened to the "electrical" here?)
- opposite charges moving in opposite directions: electrical current
- etc. etc.

Just my 2 cents, before I leave for the day.

Apparently 4 cents

I agree with Tusenfem. Useage by physicists rarely calls current flows electricity. The only place I end up using 'electricity' as a term is in circuts. When not talking about actual circuts, I use the same terminology as listed above.

[EDG]

I agree with Tusenfem. Useage by physicists rarely calls current flows electricity. The only place I end up using 'electricity' as a term is in circuts.

I think that's what confused me on the ATM thread, the guy was talking about electricity around Saturn and I just couldn't grasp what he could possibly have meant by it, since I usually think of electricity as lightning bolts or stuff flowing through wires.

[papageno]

As somebody who has worked with conductors in Solid State Physics, I confirm what tusenfem and korjik said: physicists do not use "electricity" as a technical term.

[rebel]

Last week I crawled under my machine at work to get a closer look at the "swirling coolant", I found that the electric motor that was about 8 inches above it was blowing the coolant with air from its fan. This fan was hitting the coolant just right causing the two swirls and looking like as though it was being magnetized. Sorry about all the concern, but I didn't have a chance to get under there before.

[hhEb09'1]

Good post, rebel, we may use that as an example some day

[coliver]

Dyerwolf, I have a post in the ATM section "Universe is Round"concerning a hypothesis that may provide for just what you are asking? The problem is that whenever an electrical field is produced so is a Magnetic one and visa versa. I personally believe that it can be overcome by supercooling one side of opposing magnets but I havent conducted experiments to verifty it yet?