[sdiy] MRI time dilation?

[Rob]

----- Original Message -----
From: "KA4HJH" <ka4hjh at gte.net>
To: <synth-diy at node12b53.a2000.nl>
Sent: Monday, February 19, 2001 1:14 AM
Subject: Re: [sdiy] MRI time dilation?


> >from what I remember messing with the stuff as a kid, no.. copper and
> >aluminum just do not conduct magnetic flux very well. The windings
> >themselves can be copper or aluminum, but the flux that is induced should
> >have a xfer material be ferrous to get good flux xfer ratio. There is
> >actually charts that show the flux acceptance/reluctance for various
> >materials.
>
> I don't know the physics behind this but I've seen the aluminum ring
> demonstration a number of times. Put an aluminum ring on an electromagnet
> connected to an AC supply. Switch it on. The ring goes flying off the
core.
> You shouldn't be standing in front of it when you switch it on.
>
> As I recall their are non-ferrous metals in the rotor of a shaded-pole
> motor, which works on a similar principle. All conductors interact with
> magnetic fields, just not the same way. Most permanent magnets are
actually
> alloys of ferrous (iron, nickel, cobalt) and non-ferrous metals. I leave
it
> to our resident experts to explain why...

Its to limit hysteresis by limiting the size of the domains built up during
exposure to magnetic fields..

All the other stuff is a wash. ;)

Rob