Neodymium Magnetic Cubes

AndiFlatland | 14:27 Sat 05th Jan 2013 | Science

5 Answers

I was thinking of buying one of these - plenty available on Amazon - but suddenly had a moment of apprehension: I keep a very large private archive of audio and video recordings from radio and TV, and everything is still on audio/video tape. Is the magnetism from neodymium, being much stronger than ordinary ferric magnets, also more far-reaching? I'm wondering just how far away from the magnetic tapes would be a safe distance to put it - which is not easy, as my flat is crammed full of the things!

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Hymie

Any Magnetic field strength follows the inverse square law; whereby the intensity is proportional to the square of the distance from the source. Which partly explains why the permanent magnets within your speakers have not wiped the tapes.

However my advice (to be on the safe side) would be to ensure that no magnets come within a metre of any magnetic recorded medium.

Once you have the Neodymium Magnetic Cube you could conduct experiments and find out how close they need to get to affect the recording.

heathfield

I'd also suggest around a metre distant from any magnetically recorded media, including audio and visual tapes, floppy discs, your credit and debit cards, but also any clocks or watches. By the way, their sale is banned in Australia.

Hymie

I believe that these magnets are banned in Australia because children have been swallowing them, mistaking them for sweets – and not solely because of their powerful magnetic properties.

Teddio

Neodymium magnets as curiosity items or toys are an absolute menace. They are brittle and pieces break off very easily. If you have lots of priceless magnetic recordings dotted all over the place it's not worth the risk.
Incidentally, the magnetic flux density is inversely proportional to the distance (not inversely proportional to the square of the distance) for a current-carrying straight wire. I don't want to start a debate on the hazards of living near to power lines !