magnets and credit cards

[david beer]

Daft question maybe, does a magnet damage a credit card strip? or is it a bit of an overkill to keep them at twenty paces.

[alan_driver]

i hope not cos mine is on my speakers! They can damage them, but its not easy to do so. but they do bend from the heat of a radiator if left in a jacket or something.

[beano1197]

It can do - never had a problem myself, but I would always keep cards away from things like magnetic tank bags.

[wedg1e]

I calibrate magnetic particle machines at work: they have warnings on them for people with pacemakers, but I've not found any of my credit cards to be affected (6000 Amps creates a hell of a magnetic field!).

Ian

[CraigAlsop]

If it's a strong magnet yes - you can easily test this out when you get a new bank card (but the old one is still valid for a few days)
Just rub the magnet down the strip of your old card a few times & voila! one knackered card. Test this by trying to use an ATM.
All done in the name of science with an old speaker magnet.
(Its amazing how many people believe/disbelieve stuff without testing things themselves)

[Fatboy]

I used to go into the NMR rooms in the lab (17T magnets!!!) and hold my keys next to the case to watch them all go horizontal, and that never wiped any of my cards - I'd guess you'd have to literally wipe a very strong magnet over the strip to erase it...

[CraigAlsop]

Maybe the action of wiping the magnet along it was what did it.
Mind you, the only NMR lab that I've ever been to, they told us to make sure we didn't have any credit cards on us, as they were liable to be wiped by the magnetic fields.
Also if you look on many shop counters that have the electronic tag demagnatisers (like in computer games shops for example), they all have warnings about putting your credit cards on them.

>> Edited by CraigAlsop on Monday 16th December 02:18