Magnets vs ATM cards

For some time I have been… let’s say, mildly annoyed, at what I see as a cultural paranoia regarding magnets. This has come about, imho, due to the prevalence of ATM cards for finances, harddrives for data storage, and an unawareness of what it takes to magnetically corrupt these media. I even had a friend (who works in IT!) make strong worrying noises once about data corruption on my hard drives simply because I had a fridge magnet applied to the outside of my case.

Now whilst I was certain that was not a problem, I confess to general ignorance on the subject, and so I intended to do something to correct it. Something a little fun.

Thus, when I recieved the replacement for one of my older ATM cards, I ventured to my nearest ATM with magnets and a plan. Three magnets to be precise. A very weak fridge magnet, a strong fridge magnet (both these of the ‘flexible plastic’ variety), and a small (10x20x3mm) rare earth magnet.

So how much magnetism on the card would stop it working?

I’ll cut to the chase…
Both fridge magnets had no apparent effect after a 1 second swipe over the magnetic strip. A 10 second ‘random smearing’ by the strong fridge magnet still yielded no failure in the basic ‘show me the balance’ task.

But a one second swipe with the rare earth, and, not expectantly, the card no longer was readable. I tried two machines, same dice.

Next time: hard drives…

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