Well the past night I couldn't sleep very well because I was thinking about a certain simple setup involving a magnetic field and permanent magnets. I was thinking along the line of. What if we have a uniform magnet field, what do we need in order to accelerate another magnet in that field like shown below. Well from the first image below someone will point out that in the uniform field the attraction will equal the repulsion and thus the PM will just remain stationary. And this is perfectly true. What I realized is that you needed a monopole magnet in order to accelerate the magnet and my idea just fell apart
BUT now we go a step further and "kill" some poles. Meaning I stick two magnets together with opposing poles(see second diagram). Then that for sure will make two fields on each side and accelerate it inside of the magnetic field right??? Well I made a wm2d simulation of the first using electrostatics. I made a pretty uniform field by making a big capacitor like setup but using two poles. First I put a single magnet and yes it just stays in the middle where the fields cancel out. Then I made a setup like I illustrated with two magnets symmetrical to each other.But now the above field attracts and the below repels and it wants to go up and that's also what happens in the sim. Making that uniform field is something else but that's also easy.
http://ziosproject.com/NJ/pmAvideo.avi
Hi Broli,
Your drawings recalled my memories on Naudin's pages to this: http://jnaudin.free.fr/html/shpmm.htm
I wonder why either Stefan or Naudin or anyone else have not continued on that interesting setup?
Perhaps Stefan also could recall his memories :D
rgds, Gyula
I just tried Stefan idea's as well with this electrostatic "magnets" and it didn't work. At first it seemed to work but it instantly had a speed which stayed constant. So I figured I had to jag up the accuracy. After decreasing the simulation time step the anomaly was gone.and it kept oscillating over a small distance (with air friction it just stopped). Of course simulating magnets with electrostatics is not very accurate so who knows.
I'm still playing around with the idea I had and it seems to work good linearly. What I have to do now is make that uniform field circularly. In the real world this is easy. You just grab a hollow toroid and wind electrical wire around it, energize it and you have a nice circular magnetic field inside. But in 2d I have to hack around a bit.
I have lots of things to discuss but it's kind of boring without a crowd :'(.
I just realized wm2d can't makes electric field based on the shape of the object. Every object gets treated as a point charge, the mass midpoint being the location of that point charge. But this doesn't change one thing in the simulation. Since then it's 1 dimensional sim. And we know that the straight line between 2 charges consists of a uniform electric field so the sim is very valid.
Hello, Broli,
No, it's not THAT simple (but it is simple). Yes, you are missing something.
So, where did you get the idea that the center (red) poles are no longer there, and produce no force? The center poles vanish when you put OPPOSITE poles together.
You have simply made a quadrupole, which also produces no force in a uniform field.
The earth's magnetic field is essentially uniform. If you put ANY arrangement of magnets in a boat floating on water, will the boat begin to move? (After it's through rotating.)
Ernie Rogers
Quote from: broli on January 07, 2009, 08:17:03 AM
Well the past night I couldn't sleep very well because I was thinking about a certain simple setup involving a magnetic field and permanent magnets. I was thinking along the line of. What if we have a uniform magnet field, what do we need in order to accelerate another magnet in that field like shown below. Well from the first image below someone will point out that in the uniform field the attraction will equal the repulsion and thus the PM will just remain stationary. And this is perfectly true. What I realized is that you needed a monopole magnet in order to accelerate the magnet and my idea just fell apart
BUT now we go a step further and "kill" some poles. Meaning I stick two magnets together with opposing poles(see second diagram). Then that for sure will make two fields on each side and accelerate it inside of the magnetic field right??? Well I made a wm2d simulation of the first using electrostatics. I made a pretty uniform field by making a big capacitor like setup but using two poles. First I put a single magnet and yes it just stays in the middle where the fields cancel out. Then I made a setup like I illustrated with two magnets symmetrical to each other.But now the above field attracts and the below repels and it wants to go up and that's also what happens in the sim. Making that uniform field is something else but that's also easy.
http://ziosproject.com/NJ/pmAvideo.avi
Hi broli !
one good replication of this setup I've seen didn't work. link no longer works.
Insted of stator magnets this setup used air COIL so that rotor magnets were inside this coil
by aplying current to coil and changing strenght of that current he simmulated poles of stator permeable magnets.
rotor did not move.
rotor is not moving cause rotor, at position A and in position B distanced appart let's say 1mm (or in any other part) is experiencing
same forces so there is no delta force change and rotor has no reason to move.
Wiz