IC card demagnetization is done by placing it together with a phone in Shangtai's experiment to uncover the secrets of demagnetization

IC card demagnetization is done by placing it together with a phone in Shangtai's experiment to uncover the secrets of demagnetization
A widely circulated rumor has recently circulated: "ID cards, bank cards, and other cards cannot be placed together with mobile phones." Because when a phone calls in, it's easy to demagnetize the card." Could it really be that his bus card was demagnetized and turned into a useless card because he often left it with his phone? So, can bank cards, smart electric cards, and cafeteria meal cards be placed together with mobile phones? Under what circumstances are these cards easily demagnetized? With these questions in mind, I gathered the four different types of cards mentioned above and conducted comparative tests to verify the rumors. 
　　Test materials: bus IC card, bank card with magnetic stripe, smart electronic card with chip, HID card for meal cards, and two magnets 

Experiment 1 
　　The phone simply can't demagnetize 
　　First, lay a bus IC card flat on the table, press the card with your phone, then dial the phone with the landline. The call lasts 1 minute and 1 second. Then, I took the IC card to the corresponding machine and operated it, and found that the IC card was not invalid. 
　　They then switched to bank cards, smart cards, and HID cards to repeatedly conduct the above "demagnetization" tests, keeping each phone call lasting over one minute. However, after demagnetizing these three types of cards with a phone, it was found that all three cards could be used normally on their respective machines without demagnetization. 
　　Test conclusion: When phones are on the phone for long periods, it is easy to demagnetize cards placed together, but this claim is incorrect. 

Test 2 
　　Two magnets demagnetized the bank card 
　　First, using a magnet, I swiped the bus IC card, bank card, smart card, and HID card 50 times each, and the cards did not become demagnetized. 
　　Then a magnet was added, and the same tests were conducted on both sides of the four types of cards using two magnets. As a result, bus IC cards, smart electric cards, and HID cards were not demagnetized as a result. 
　　However, when the processed bank card was placed into the ATM, an unexpected event occurred! 
　　The green indicator light on the ATM kept flashing, followed by an alarm. A large exclamation mark appeared on the screen: "This card is invalid, please retrieve it." Two seconds after the exclamation mark appeared, the bank card was automatically ejected by the machine. 
　　He tried several times to insert this bank card into the ATM, but each time the card was spit out. After replacing an ATM, the card was still spit out. This shows that the bank card has already been "demagnetized" by the action of two magnets. 
　　Test conclusion: Strong magnets can indeed demagnetize bank cards with magnetic stripes, but they have no effect on the other three types of cards. 

Bank magnetic cards are sensitive to strong magnetic fields 
　　Regarding the case where only the bank card was demagnetized by magnets among the four cards, Associate Professor Yang Yong from the School of Electrical Engineering at Huazhong University of Science and Technology explained that this is because these four cards store different carriers of information. Currently, most bank cards are magnetic cards. The magnetic stripe on the card is either coated with liquid magnetic material or glued onto the card with a thin solid magnetic strip. If the magnetic card is affected by a strong external magnetic field, the information inside the magnetic stripe will be destroyed, making the card unusable. Therefore, magnetic cards should not be placed too close to strong magnets or objects emitting strong electromagnetic waves. However, generally speaking, the magnetic field generated by a phone is not enough to demagnetize the magnetic card. 

Contact IC cards are sensitive to static electricity 
　　Smart electronic cards with a metal surface belong to this categoryContact IC cards。 This type of card abandons the original magnetic stripe storage and uses integrated circuits to store information. For example, mobile SIM cards are all types of contact IC cards. However, Professor Yang pointed out that this type of card connects the reader to the card's internal circuitry through several contacts to complete information exchange, and the card's read and write data is directly powered rather than read/write. 
　　Therefore, this type of card basically does not have the issue of "demagnetization." However, contact IC cards also have weaknesses, such as wear and static electricity. "In winter, static electricity can form on clothing, sometimes reaching thousands of volts, which can damage the parts where the card's information is stored. Therefore, when using these cards, attention must be paid to anti-static measures. ” 

Contactless IC cards are prone to dents and breaks 

　　Bus IC cards belong toContactless IC cardsOther cards of the same type include thick HID cards, ID cards, and so on. Its essential structure is not much different from contact IC cards, except it converts the original metal contact setup into wireless transceiver. Its working principle is that the card reader emits electromagnetic waves that change based on information. The induction coil inside the IC card converts these electromagnetic waves into induced current, which is used to transmit information and drive the chip operation. 
　　Regarding Ms. Li's confusion, Professor Yang believes it may be because the card repeatedly folds during frequent swiping, causing damage to the coil inside. Additionally, if a contactless IC card is placed next to a computer or other highly radiated electrical device, the current generated by the radiation will repeatedly pass through the induction coil inside the card, which can also damage its lifespan.