TIME said:
what size magnet would you have to have to delete everything on a video
tape or dvd disk ? ej.
For video tape, it'll depend on the composition and how complete you
need the erasure, but based on this page:
http://www.periphman.com/degaussing/degaussers/mds4.shtml
It looks like something in the order of 1500-2500 Oersteds. This is
assuming the video tape case isn't shielded against magnetic fields.
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For a DVD disc, that'll be a bit harder, as it's an optical storage
medium. I could say a magnet won't affect it, but seeing as a strong
enough magnetic field could theoretically warp space, I guess it's not
impossible. A field strength that strong wouldn't be particularly
healthy for humans though. In more sane terms, just forget it. You're
not likely to get hold of a magnet strong enough to erase a DVD using
its magnetic field. You might be able to magnetize something big and
heavy enough to physically pulverize the disc, but it'd be so much
easier just to snap the disc with your bare hands or feed it to a shredder.
