full-disclosure - Re: erase with magnet

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Message-ID: <20040403202311.GB9387@positron.mit.edu>
From: rsw at jfet.org (Riad S. Wahby)
Subject: Re: erase with magnet

Caraciola <caraciola@....net> wrote:
> casing. Then you could try alternating magnetic fields, with enough strength 
> to induce electric currents in the casing, which would possibly produce 
> strong enough magnetic fields in the interior,

Your physics is backwards here.  The conductive casing of the hard
drive will tend to reject magnetic fields inside.  More precisely, the
current you induce will produce a field in the opposite direction from
the one you're applying, and the superposition of the two will result
in a net smaller magnetic field inside the drive.  That is, unless you
can find a hard drive whose casing has a negative resistance.  :-)

See, for example, Zahn's "Electromagnetic Field Theory: A Problem
Solving Approach."

-- 
Riad Wahby
rsw@...t.org
MIT VI-2 M.Eng