Non-diy_efi, dyno help

[Pat Ford]

Previously, you (David Cooley) wrote:
> At 12:09 PM 6/18/99 -0400, you wrote:
> >
> > Yes but eddy currents are not magnetic, they are electric.
> > Have you ever wondered why transformer cores are made of little plates
> >rather then a solid chunk of iron?? Read on Mc Duff
> >
> >> 
> 
> Yes, but the two are inter-related...   Changing magnetic fields induce
> electrical eddy currents in metals, and those eddy currents generate
> magnetic fields that oppose the fields that cause the electrical eddy currents.
> 
> I used to demonstrate this when I worked on MRI systems...  I'd take an
> Aluminum sign, 3/32" thick (not critical as to composition, just any
> non-magnetic metal works) and stand it up on edge in the bore of the MRI
> magnet (1 Tesla or 1.5 Tesla Superconducting magnet).

watch out for metal wrist matches eh?

> and give it a tap to
> knock it over... It would take between 15 and 30 seconds to fall depending
> on which one of the 2 magnets it was in...

cool, sounds like the same type of demo as the aluminum ring and an electro 
magnet ( you know the one where the ring floats)

> You can also hold it and wave it like a fan in the bore of the magnet and
> it feels like it's under water and actually flexes and bends as you move it
> through the field due to the eddy current induced magnetic field in the
> plate (sign) that opposes the main MRI magnet's field.
> Later,
> Dave

 I was trying to clear up the eddy current stuff to something that could easily 
be visualized, you are right I should have mentioned the relationship but I 
hit send too early.

Sounds like a nice job, being able to play with big toys 8)

> 
> =========================================================== 
> David Cooley N5XMT Internet: N5XMT at bellsouth.net 
> Packet: N5XMT at KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068 
> We are Borg... Prepare to be assimilated! 
> ===========================================================
> 

--
Pat Ford                           email: pford at qnx.com
QNX Software Systems, Ltd.           WWW: http://www.qnx.com
(613) 591-0931      (voice)         mail: 175 Terrence Matthews          
(613) 591-3579      (fax)                 Kanata, Ontario, Canada K2M 1W8