Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: that mad man on 26/09/2009 23:28:31

Title: bar magnet into ring magnet?
Post by: that mad man on 26/09/2009 23:28:31

Hi.

If I take a longish bar magnet and bent it into a circle, connecting North to South, what then happens to the poles positions? Do they cancel out and it stops being magnetised or do they change positions? If its the latter then why?

All I've got is a bar magnet and no strength to bend it so I hope spinach is not the answer. [;D]

Title: bar magnet into ring magnet?
Post by: RD on 27/09/2009 01:02:21

Ring = torus (http://en.wikipedia.org/wiki/Torus) => toroid(al) ...

http://van.physics.illinois.edu/qa/listing.php?id=397

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/toroid.html

Title: bar magnet into ring magnet?
Post by: that mad man on 27/09/2009 18:16:41

Thanks again RD. [:)]

I remember having some of those on a wooden dowel N to N and S to S so they levitated, fun stuff. I was messing about at the time with an idea for frictionless bearings.

But referring to the bent bar magnet, the first link says "no point is more N-like or S-like. Therefore a toroidal magnet has no poles" and yet we know toroids with poles do exist so I'm still a bit confused.

Its easy to make a ring magnet with poles on the sides but a bent bar magnet seems to retain a magnetic field and yet have no poles. If the poles in this case do migrate to the sides when the ring is formed then its the mechanism that causes this I'm after.

Title: bar magnet into ring magnet?
Post by: that mad man on 27/09/2009 18:19:23

Huh..

What happened to the previous posts?