Fact or Fable? Cell Phones Damage Cards That Use Magnetic Strips
This is a fable. You may have been warned at some point by a hotel employee to keep your key card away from your cell phone for fear that the phone’s magnetic field might demagnetize the strip on the back of the card, rendering it useless. While a cell phone does emit a magnetic force, it is much too small to damage a hotel key card, credit card, or similar types of cards.
The black magnetic strips located on the backs of key cards, credit cards, and so on, contain important information. On a credit card for example, it stores the cardholder’s name, account number, pin number, expiration date, country of issuance, a security code, and other pertinent data. Standards set forth by the International Organization of Standardization (ISO) specify magnetic strip content, including the type of information stored, information format, and the way in which the information is coded.
Scanners read the programmed information on magnetic strips, which is encoded on tiny iron particles. These particles are aligned on a magnetic field, which means the data contained on the strip may be vulnerable to demagnetization by other items with magnetic fields stronger than that of the card. In other words, demagnetization occurs when one magnet outperforms the other. If this happened, the stronger magnet would scramble the information encoded on your card’s magnetic strip. That is why if you are scheduled for a MRI (magnetic resonance imaging), you should leave your credit cards behind since there are very large magnetic fields involved.Despite this, cards that adhere to ISO standards are nearly impossible to demagnetize with magnets available to the general public, including refrigerator magnets or the magnetic field of a cell phone. If you think you have been a victim of cell phone demagnetization, chances are the magnetic strip was actually corrupted by scratches or small bends. Even minor scratches can damage your card, leaving it unreadable.