Sliding Magnet

[duffy]

No, seems like they would always magnetize it the same way, and it's probably sitting on top of a solenoidal field. So because there's thickness to the magnet, there's a change in divergence from top to bottom. That difference would account for the behavior, the eddy currents in the aluminum would be proportional to the flux density, which is different because of the way the field diverges.

 

[j.friend]

Ok i'll try and explain it again...

In the manufacture of magnets, each magnet in a batch would have a slightly different magnetic fields due to the induced magnetic field from the solenoid (or whatever the origin for the magnetism). If the alignment of these fields are the cause for the tumbling/sliding effect, then surely there would be cases where it would be the north pole down instead of the south pole down that will result in tumbling rather than sliding. (Whichever way around it is)

As all the cases that I've heard of are all the south pole reacting in the same way it would seem to me that it is not the slight differences in the magnetic field of the magent that are the casue for this phenomenon.

However if you could show that the effect is extenuated with magnets with a proven more skewed magnetic field, this theory would be more plausible.

it makes sense to me so i hope I have come across semi-understandable

 

[duffy]

Gee, thanks, but I understood you the first time. You're ignoring the change in divergence of the field, the one I've mentioned in more than one reply now. This would always be on the same pole, and seems to be the most straightforward answer.

I'll even draw you a picture -

 

[j.friend]

Ok, sorry i was unawares that that was how magnets were positioned to be 'magnified'. for some reason I was under the impression that magnets were positioned laterally across the solenoid which would result in a difference along the magnetic field.

Why would the solenoid always have the north pole at the top and is this magnet making regulation or a coincedence?

I can certainly see that this would be a very plausible reason as to why this phenomenon exists

 

[duffy]

They aren't going to reverse the field in the fixture for every other magnet, it's going to be a DC supply and a switch than can handle a high current pulse.

 

[j.friend]

Yeah i realise that, however not all magnets are manufactured in the same plae using the same solenoid. I was just wondering if you might have known whether it is general practise (for all manufacturers of magnets) to magnetise the magnets at the positive end of the solenoid.

I know its a bit obscure but unless it is, or by coincedence/other reason it is, there would be magnets where that field chareacteristic would be opposite, meaning that the phenomenon would not be exclusively happen for the south poles of a magnet....

I'm sorry for being a bit of a stickler

 

[duffy]

It's not the positive end that determines the north pole. Google "right hand rule".

 

[j.friend]

I know about that and I know how to determine the 'path of North monopoles" in a magnetic field. All I'm saying is if the magnet was created over the south pole of the solenoid instead, the field would be reversed. Using the same solenoid and simply reversed the electrodes would cause a swap in the magnetic field of the solenoid

 

[Pommie]

Wouldn't it make more sense to place the magnet in a small gap in the magnetic circuit. Any airgap would increase the reluctance and require more ampere turns to produce the same flux. Or do I need to brush up on my magnetic circuits.

Mike.