# magnets coupled with electricity

## Recommended Posts

why dont magnets affect an electric stream

##### Share on other sites

they do affect electric currents. specifically, they will provide a force perpendicular to the flow of current and the magnetic field.

moving a magnet over a metal plate will also induce electric currents in the plate.

this is the whole principle behind electric motors.

##### Share on other sites

Hold a magnet near a AC transformer, you can feel the magnet vibrate.

##### Share on other sites

I think i might have to clarify what i am questioning.

why does the magnetic fields not affect visibly the electrical stream between 2 points of a electric arc.

##### Share on other sites

:confused:Maybe because the currents of each are opposite of each other that they barely affect each other unless the magnetic force is greater than the electrical current. I'm not sure.

##### Share on other sites

hmm.. i dont know, iv used some pretty poowerful magnets against both arc between a cut wire and a lightning bolt from a teslacoil, both on the bolt in air, and when the coil is near enough to an object to arc

##### Share on other sites

That is not a changing magnetic field though. A static magnetic field doesn't do much to electric current (barring the Hall effect). A changing magnetic field will induce currents in conductors, which may produce a noticeable effect on your arcs. I doubt very much that you will see any effect, however, since the magnetic field needs to be very strong, and the resistance in the conductor needs to be fairly low for noticeable effects to be seen. I think you will fall short on both accounts, as the tesla coil will probably fry any power transistors you could use for creating a changing magnetic field, and the arc itself has a fairly high resistance.

You may be able to see effects if you use compressed air to blow the arc into a magnetic field, as the magnetic field can bend the path of charged particles. The effect may be too small to notice however.

##### Share on other sites

so what would then be the proportion of magnetic fields producing electric current?

I find it very hard to believe that a magnet can so easily produce a current but have a near nill affect on a current.

Maby it would be better to study the affects of magentism not on electricity but on plasma

##### Share on other sites

That is not a changing magnetic field though. A static magnetic field doesn't do much to electric current (barring the Hall effect).

But it would be the Hall effect/Lorentz force we're looking at.

F = qv X B

If you indeed see no deflection, one problem might be that the electrons in an arc may be moving quite fast, so there isn't much time to observe a deflection over a short path. The path being in air and the ionizations may have an effect. However, I've played with CRTs and magnets, and the electron beam is indeed affected by the magnetic field.

##### Share on other sites

hmm, i wil take that into consideration next time i review the effects of magnetic fields on electric current.

however, could you please explain the equation, i have taken highschool physics, and will be taking physics later on once i get into college after the airforce

could you also refrence an equation for the strength of an magentic force, with force applied in a circular motion to create electricity. I would like to compare the forces involved

##### Share on other sites

If you indeed see no deflection, one problem might be that the electrons in an arc may be moving quite fast, so there isn't much time to observe a deflection over a short path. The path being in air and the ionizations may have an effect. However, I've played with CRTs and magnets, and the electron beam is indeed affected by the magnetic field.

I figured the atoms would be trading electrons with each other, rather than there being large numbers of free electrons traveling significant distances. The air pressure is too high for that. I figured that the behavior of the arc would be similar to the behavior of a wire.

If he tried blowing the arc with something, it might get the ionized air moving at appropriate velocities to be deflected by a field.

##### Share on other sites

The arc is probably ac, so the direction of deflection reverses many times a second. No noticable net deflection will be seen. Try with a dc arc welder.

##### Share on other sites

hmm, i wil take that into consideration next time i review the effects of magnetic fields on electric current.

however, could you please explain the equation, i have taken highschool physics, and will be taking physics later on once i get into college after the airforce

could you also refrence an equation for the strength of an magentic force, with force applied in a circular motion to create electricity. I would like to compare the forces involved

$F = q\vec v \times \vec B$ where

F = force

q = charge

$\vec v$ = velocity of charge with respect to the magnetic field

$\vec B$ = strength of magnetic field

Vectors (marked with an arrow over their letter) represent a magnitude and direction. The X is a cross product, which takes two vectors and results in one vector that has a direction perpendicular to both, with a magnitude of the product of the magnitudes of each and the sine of the angle in between.

##### Share on other sites

Magnetic quenching is also used in some Spark-Gaps too.

##### Share on other sites

thank you so much for the equation, iv been looking for it for quite some time.

sadly its been quite a while and i will have to restudy up to fully understand the equation

##### Share on other sites

Magnetic quenching is also used in some Spark-Gaps too.

And in high current relays and and switches. But a permanent magnet won't work with an AC current. You need to use an electromagnet so that the cross product of the current element and the magnetic field doesn't reverse 60 times a second.

## Create an account

Register a new account