sci.physics.electromag

Paul wrote:
> On Apr 4, 4:25???pm, j...@specsol.spam.sux.com wrote:
> > Paul wrote:
> > > On Apr 4, 10:14?am, Benj wrote:
> > > > On Apr 3, 9:25 pm, j...@specsol.spam.sux.com wrote:
> >
> > > > > A non-magnetic cage around a compass will have no effect, conductivity
> > > > > isn't the issue for static magnetic fields.
> >
> > > > What Jim means it a conductive enclosure (provided it isn't TOO
> > > > conductive) won't effect the static readings of the compass. (a
> > > > superconducting enclosure would block magnetic fields) On the other
> > > > hand the conductive enclosure could affect the speed of response of
> > > > the compass due to eddy current effects as the magnetic field is
> > > > changed or the device moved in that field. ?How much it affects the
> > > > the response depends on the details of the construction, of course.
> > > ??? ??? ??? ??? ???Are you saying that the magnetic field will not
> > > be distorted due to a non-magnetic, but conducting cage?
> > > ??? ??? ??? ??? ???Both the compass and the cage will move within the
> > > field.
> >
> > Moving a conductor in a magnetic field will induce current, called
> > eddy currents, in the conductor, which in turn cause magnetic
> > fields.
> >
> > The magnitude of those induced fields will be proportional to the
> > magnitude of the external field and the velocity of the conductor.
> >
> > Unless the external magnetic field is a lot greater than the Earth's
> > and the conductor is moving really fast and is really close to the
> > compass, you are unlikely to see any effect.
> >
> > However, accelerating or turning a compass will cause compass errors
> > all by itself. I'm assuming an ordinary mechanical compass here.
> >
> > --
> > Jim Pennino
> >
> > Remove .spam.sux to reply.- Hide quoted text -
> >
> > - Show quoted text -

> This will be a digital compass, with MEMS
> accelerometers.

> Are you saying that the magnetic field will
> not be distorted due to a non-magnetic, but
> conducting cage? As if the cage wasn't there?

If the cage is not moving relative to the field, no distortion.

If otherwise, see above.

--
Jim Pennino

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