If you cannot swipe the China Merchants Bank credit card with a chip, it is because the chip on the card has been degaussed.

What is "degaussing"?

Degaussing means that the magnetic particles on the magnetic card lose their original magnetism. Generally speaking, there are three reasons for degaussing, one is external impact, the other is high temperature, and the third is strong magnetic field. If you put your bank card near your mobile phone, it will cause interference from the magnetic field.

The working principle of bank cards

First of all, let’s introduce the working principles of bank cards and magnetic cards. Generally speaking, a bank card is a card that uses "magnetism" to store information. Depending on the base material (plastic board), magnetic cards can be divided into three types: PET cards, PVC cards and paper cards. If classified according to the magnetic structure, they are divided into two types: magnetic stripe cards and full magnetic cards.

At present, the vast majority of bank cards are magnetic cards, with many small particles of ferromagnetic material evenly distributed on the magnetic strip on the back. We can think of these small particles as small compasses one by one. When the directions of these little compasses are out of order, the magnetic strips do not exhibit magnetism. But when all the little compasses point in the same direction, they will exhibit magnetism.

If the surface of the magnetic strip is divided into many small grids and the magnetism of each grid is controlled individually, the magnetic strip will carry information. When the bank card leaves the factory, the magnetic head of the card writer will emit a changing magnetic field, changing the magnetic field of each small grid on the magnetic strip, thereby writing the card number and other information onto the magnetic strip. The bank links the account you established in the bank's computer system with the card number stored on the bank card. This way you can use this bank card to access your account.