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TBT: Debunking the demagnetized card myth

In honor of Throwback Thursday, each week we’re going to pull and review a story from the CR80News archives. With any luck, in the time since these stories originally broke some form of progress will have been made, predictions will have come true — or not — and at the very least we can sit back and wonder what we were thinking.

The first edition of Throwback Thursday isn’t the furthest jump back in time, but it’s one of CR80News’ most highly trafficked stories year after year. It’s the infamous “cell phone demagnetizing a key card” myth. This story has been so popular over the years that it merited an update in 2011, and still the hits keep coming.

Citing a CPI Card Group study conducted in 2009, card users experienced issues while carrying mag stripe movie theater cards in their pockets with a cell phone.

Crucially, though, mag stripes vary in their coercivity, with higher coercivity stripes — typically deployed on credit cards — being more resistant to demagnetization than hotel key cards that traditionally fall lower on the coercivity scale. The lower the coercivity the more susceptible the card will be to demagnetization, but questions have long existed as to whether a cell phone has a powerful enough magnetic force to impact even a low coercivity card.

It’s not clear exactly why this story remains so popular years after being published, but with mag stripe technology still a mainstay on a great number of college campuses nationwide, it is clear that fundamental questions surrounding mag stripe technology are still being asked.

From 2011, here’s Mythbusters: Can a mobile phone erase a hotel key card?

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