moving charges and charge carriers

[DandelionTheory]

so current through a conductor induces an external magnetic field according to this site:

https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/magnetic-field-around-a-wire-i

 

i understand current is described as a net motion of charge carriers in a conductor, but what about moving charge carriers that are fluid?

 

my question is if the charge carrier was a chemical like copper sulfate, do the same rules apply if the copper sulfate's path of motion was confined to a pipe or tube?

would the same rules that apply to current in a loop apply to copper sulfate moving in a coil/loop?

Edited December 19, 2019 by DandelionTheory

[Strange]

The trouble is that copper sulfate is electrically neutral; which means you have the same number of positive and negative charge carriers moving in the same direction. The magnetic fields generated by these will cancel out. In the case of a current through a wire you have the moevement of electrons only and so a magnetic field is produced.

If you could arrange to get a flow of just sulfate ions (or just copper ions) then you would get a magnetic field. But I am not aware of any way of doing that.

But a solution of copper sulfate is conductive, so presumably you could pass a current along the tube, and it would act like a wire

[DandelionTheory]

thank you for your reply,

i have an additional question to add to your answer:

if the conductor was fluid, would the net motion of the charge carriers be greater than with a non fluid conductor with the same applied current?

i guess what i'm asking is does resistance decrease with conductor viscosity?

[Strange]

4 minutes ago, DandelionTheory said:

thank you for your reply,

i have an additional question to add to your answer:

if the conductor was fluid, would the net motion of the charge carriers be greater than with a non fluid conductor with the same applied current?

i guess what i'm asking is does resistance decrease with conductor viscosity?

Interesting question. I don't know if there is any direct connection like that. The conductivity of the conductor depends on how free the electrons (or other charge carriers) are to move. This is why metals are good conductors: lots of electrons free to move.

Would liquid mercury be a better conductor than solid mercury (below its melting point)? I really don't know.

[studiot]

4 hours ago, DandelionTheory said:

i understand current is described as a net motion of charge carriers in a conductor, but what about moving charge carriers that are fluid?

 

my question is if the charge carrier was a chemical like copper sulfate, do the same rules apply if the copper sulfate's path of motion was confined to a pipe or tube?

would the same rules that apply to current in a loop apply to copper sulfate moving in a coil/loop?

 

3 hours ago, Strange said:

The trouble is that copper sulfate is electrically neutral; which means you have the same number of positive and negative charge carriers moving in the same direction. The magnetic fields generated by these will cancel out. In the case of a current through a wire you have the moevement of electrons only and so a magnetic field is produced.

If you could arrange to get a flow of just sulfate ions (or just copper ions) then you would get a magnetic field. But I am not aware of any way of doing that.

But a solution of copper sulfate is conductive, so presumably you could pass a current along the tube, and it would act like a wire

 

 

Yes and no.

 

Quote

Magnetohydrodynamics (MHD; also magneto-fluid dynamics or hydro­magnetics) is the study of the magnetic properties and behaviour of electrically conducting fluids. Examples of such magneto­fluids include plasmas, liquid metals, salt water, and electrolytes.

https://en.wikipedia.org/wiki/Magnetohydrodynamics

 

Fluids and fluid mechanics includes  liquids, gases and plasmas.

Magnetohydrodynamics started off studying the interaction between the mechanical properties and th electrical properties of gases and plasmas though its ambit seems to have been extended to include liquids and solutions such as copper sulphate solution.

I suppose this was because there is a very marked difference between those interactions when the fluid is a plasma or gas and when it is a solution or liquid.
In gases as against liquids, the fluid velocities tend to be much larger, the densities much lower so the particles have much more space to operate in.
This significantly affects the interactions.

In plasmas and gases (compressible fluids) the average distance between particles is large but subject to large mechanical interactions that can bring them close together.
These effects include Venturi effects, Sonic effects (Alven waves) , Shockwaves.

In solutions the ions are close together and interact electrostatically to produces such effects as polarisation and overpotential, effects hardly seen in gases.

So yes

Copper sulphate solution is electrically neutral overall and it contains ions, both positive and negative.
Both ions can move and will do so selectively under the influence of an electric field, otherwise they move about randomly in solution. They do not separate but remain mixed up.
With an electric field the negative ones move towards what is called the cathode and positive ones move towards the anode.
This means there is an equal and opposite current of positive ions moving one way and negative ones moving in the opposite direction.
But this only happens if there is an externally connected circuit. Electrons then enter the solutions at the anode and leave at the cathode via this connection.
The total current is thus the sum of both ionic magnitudes.
There are no free electrons in solution.

 @ Strange Connecting wires are also electrically neutral. Electrons enter at one end and leave at the other.

 

The addition of an external magnetic field raises more interaction possibilities, particularly for fast moving gaseous and plasma charged particles.

In summary, in solutions electrical resistance (conduuctance) dominates the electrical side of the interaction and compression density dominates the mechanical side.

Whilst in plasmas and gases reactive impedance effects dominate the electrical effects and density chages the mechanical ones.

 

Please note this is a very broad brush treatment and this is currently a rapidly developing Science.

Edited December 19, 2019 by studiot

[Sensei]

https://physics.aps.org/story/v19/st3

"A tank of stirred liquid sodium generates a magnetic field even though it’s highly turbulent–a condition closer to real dynamos in planets, stars, and galaxies, but harder to simulate in the lab."

More articles about it

https://www.google.com/search?q=liquid+sodium+magnetic+field

 

Edited December 19, 2019 by Sensei

[Strange]

1 hour ago, studiot said:

@ Strange Connecting wires are also electrically neutral. Electrons enter at one end and leave at the other.

I thought that is what I said. Well, it is what I intended to say!

 

1 hour ago, studiot said:

Yes and no.

Teamwork: I do the "no" and you do the "but also yes"

[DandelionTheory]

so if copper sulfate was in a tube, where it had a 90 degree bend and electrodes were on each end of the tube electrically connected to the copper sulfate; i want to know if the moving charges are the same calculation when i attempt to do a summation of forces over time. 

because if the electric field is AC, the moving charges would always interact at the 90 degree bend. right? o.O

[DandelionTheory]

The magnetic force on a moving charge reveals the sign of the charge carriers in a conductor. A current flowing from right to left in a conductor can be the result of positive charge carriers moving from right to left or negative charges moving from left to right, or some combination of each. When a conductor is placed in a B field perpendicular to the current, the magnetic force on both types of charge carriers is in the same direction.

from:

https://www.britannica.com/science/Lorentz-force

On 12/19/2019 at 6:20 PM, DandelionTheory said:

because if the electric field is AC, the moving charges would always interact at the 90 degree bend. right? o.O

so if an aqueous salt has both charge carriers and the electric field applied was ac, the Lorentz force would mean each charge carrier interacts with another's magnetic field at a right angle. My point is the average in momentum does not balance out, and there is a net force inline with the right angle bisector.

 

[studiot]

1 hour ago, DandelionTheory said:

The magnetic force on a moving charge reveals the sign of the charge carriers in a conductor. A current flowing from right to left in a conductor can be the result of positive charge carriers moving from right to left or negative charges moving from left to right, or some combination of each. When a conductor is placed in a B field perpendicular to the current, the magnetic force on both types of charge carriers is in the same direction.

from:

https://www.britannica.com/science/Lorentz-force

so if an aqueous salt has both charge carriers and the electric field applied was ac, the Lorentz force would mean each charge carrier interacts with another's magnetic field at a right angle. My point is the average in momentum does not balance out, and there is a net force inline with the right angle bisector.

 

There is a force on any elbow carrying a flowing fluid due to the destruction of momentum in the forward direction and creation of momentum in the perpendicular one.

Momentum therefore does not balance without the force.

 

[DandelionTheory]

3 hours ago, studiot said:

There is a force on any elbow carrying a flowing fluid due to the destruction of momentum in the forward direction and creation of momentum in the perpendicular one.

Momentum therefore does not balance without the force.

 

Are you considering charged fluid? This idea would mean any magnetic field would add to the change in momentum of the fluid, meaning all moving charge carrier's magnetic field would do work on any perpendicular charge carrier in the field.