Sihai network

Will mobile phones demagnetize bank cards? Can mobile phones and bank cards be put together

4hw.org: there are many common sense misunderstandings in our life that often mislead us, such as cell phones, bank cards, ID cards and other cards. Otherwise, cell phones will eliminate the magnetism of these homes, and cards and cards can't be put together. Is that true? Let's see the truth of the incident!

Truth: you may come into contact with various cards in your daily life, such as bus card, second-generation ID card, canteen meal card, community access card, IC phone card, bank card, etc. Only the magnetic card with magnetic stripe on the back can be demagnetized. Cards without magnetic stripe, such as bus cards, canteen meal cards, community access cards and second-generation ID cards, are all contactless smart cards using RFID technology, while IC phone cards are contact smart cards. The information of these smart cards is stored on semiconductor chips. Without the use of magnetic recording technology, it is impossible to 'demagnetize'.

The vast majority of bank cards are magnetic cards, and the magnetic stripe on the back of them is evenly distributed with many small particles of ferromagnetic materials. You can think of these little particles as little compasses one by one. When the direction of these little compass is disordered, the magnetic stripe does not show magnetism. But when all the little compasses are in the same direction, they show magnetism. If the surface of the magnetic stripe is divided into many small grids, and the magnetism of each grid is controlled separately, the magnetic stripe contains information. When the bank card leaves the factory, the magnetic head of the card writer will send out a changing magnetic field, change the magnetic field of each small cell on the magnetic stripe, thus writing the card number and other information to the magnetic stripe (this is the same principle as the tape recorder). The bank connects the account you set up in the bank computer system with the card number stored on the bank card. So you can use this card to access your account.

Since the magnetic field is used to write information to the bank card, the reasonable inference is that when the bank card is close to a strong magnetic field (such as a magnet), its original stored information will be rewritten, thus losing information. This process is called degaussing.

According to the rumor, the electromagnetic wave generated when the mobile phone works will demagnetize the bank card - this is impossible. The frequency of electromagnetic wave emitted by mobile phone is between 850mhz in UHF band and 2.4GHz in microwave band. In this frequency range, the main energy form of electromagnetic wave is electric field, which will not produce a magnetic field sufficient to change the magnetic strip information on the bank card. What, don't you believe it? The experimental Party of guoke.com has personally verified this statement. The electromagnetic wave emitted by the mobile phone can't make the bank card demagnetize.

However, some parts of the phone do have magnets. For example, loudspeaker and vibration motor. So if the loudspeaker of the mobile phone and the magnetic strip of the bank card are pressed together, will it make the bank card demagnetize? In theory, as long as the magnetic field is strong enough, it is possible. However, what's the actual situation? Please go out of the apple shell network experiment party! It's not enough to demagnetize the bank card by pressing some common cell phone handset parts against the bank card. With the increase of distance, the magnetic induction intensity will decrease with the square of distance. Maybe the installation position of mobile phone speaker and vibration motor makes them not close to the magnetic strip of the bank card, and can not play the effect of demagnetization. In order to prove this possibility, the Guoke network experimental party even took apart a Sony Ericsson mobile phone, took out its loudspeaker and vibration motor, which were close to the magnetic strip of the bank card, and could not demagnetize it. It is suggested that in the end, the rough experimental party destroyed a card to HLL, using a magnet block.

Now let's welcome the experimental party to toss over this bitter bank card for you. Welcome to watch the truth of card abuse.

As for the statement that 'two bank cards can't be put together, because the bank cards will demagnetize each other before' is also wrong. The magnetic induction intensity of the magnetic stripe on the bank card is very weak, which is not enough to demagnetize another bank card. The reason for this is to avoid the damage of magnetic stripe area caused by friction between cards. It is suggested that the cards should not be put together directly, but should be protected with plastic cover.

Some people worry that it's OK to put the bank card together with the mobile phone for a short time, but the bank card will slowly demagnetize after putting it together for a long time. 'it's also an assumption. Whether or not a magnetic substance will be magnetized is only related to the magnetic induction intensity, and has nothing to do with other factors. The magnetic field near the weak magnet will not become stronger as time goes on, so you don't have to worry about the demagnetization caused by putting the mobile phone and the bank card together for a long time.

Finally, it should be noted that although the magnet in the mobile phone will not demagnetize the bank card, the rumor crusher still suggests that the reader keep the bank card away from the area where strong magnetic field exists.