Ok, we’re always supposed to swipe our cards quickly.
How come? What happens if you do it slowly?
As far as I know, nothing at all. Sounds like someone is in a hurry more than anything.
I spent about a year working on a project adding companies using mag cards (utility companies, local authorities, cable companies) to a transaction-paying system, and a big part of that was checking the sample cards the client sent (for check digits, ISO-standard compliance and so on). It didn’t make much difference to the test equipment we had (which was older and in worse condition than the models out in the “real world”) what speed you swiped at.
Not that I have anything to back this up, but I always thought that it was because you are more likely to swipe at a more constant speed going fast than slow, making it easier to read.
But it sounds like Mattk actually has some knowledge in this area, so I’ll bow out.
Magnetic card readers work on the same principle as magnetic tape readers and magnetic disks: the magnetic medium is magnetized, just like a row of little magnets. Moving these magnets past a stationary object induces voltages in the object; if that object has wires (or, better yet, coils of wire) in it, you can get current as a result, and you can detect that.
The voltage induced is proportional to the rate of change of magnetic flux through the coils. So moving the card fast induces more voltage than moving the card slowly.
I hypothesize that this is the reason for the injunction to move the card fast, but I don’t know for sure. I’m sure the voltages involved must be tiny, though.
I think its a test by Big Brother to see just how gulible the public is. They watch us at gas stations and supermarkets to gather results so that when they unleash the Master Plan, they will know just how far they can minipulate the Media before we feel something is amiss.
Thats my story and I’m stickin to it.
Nothing different happens if you swipe the card slowly. Here at Michigan State U, parking is quite tight, and the graduate students’ lots are gate-controlled to keep out the hordes who descend on us for football and basketball games. I usually swipe the card through very quickly, but I’ve taken about one full second to pull it through, and the gate still opens as expected.
I imagine that if you pushed the card halfway through, then left to go to the bathroom and finished the swipe ten minutes later, the gate might not open. But I’ve never been drunk enough to try this myself 