ID card "demagnetized"? The phone is not to blame!

Audit expert: Zheng Yuanpan, professor at Zhengzhou University of Light Industry

The ID card is an important identity document in our country. It contains basic personal information such as name, date of birth, ID number, etc. It plays a vital role in all aspects of our daily life.

However, there has been a rumor circulating on the Internet that placing a mobile phone and a second-generation ID card (hereinafter referred to as the ID card) together will cause the ID card to be "demagnetized" , thereby losing its basic function of identifying personal information.

So, can an ID card be "demagnetized"? Today, let's first understand the composition of the ID card and the concept of "demagnetization", after which we can easily answer this question.

What's in the ID card?

The ID card is composed of a plastic card and a radio frequency identification (RFID) chip. The plastic card is used to protect the chip and the personal information it carries. The RFID chip is the core part of the ID card, which is used to store and transmit citizens' personal information, such as name, address, photo and fingerprint.

The principle of RFID technology is to use wireless radio frequency for communication and data transmission , which is mainly realized by RFID tags, RFID readers (also called card readers) and the data processing system behind them. RFID tags are the chips in ID cards. When an RFID tag approaches, the RFID reader will activate the nearby RFID tag by emitting electromagnetic wave signals and communicate with it. The reader will then transmit the read tag information to the data processing system, and the system will analyze, store and manage the read information to meet specific application requirements.

Source of the second-generation resident ID card: Wikipedia/Coolgene

The widespread application of this technology can provide a more convenient and secure way of identity authentication. For example, when taking a high-speed train, checking tickets on a train, going through border crossings or handling related business, the identity of the individual can be confirmed by reading the information on the chip.

Demagnetization refers to the process in which the original magnetism of an object is destroyed or weakened under certain conditions , which will cause the object to lose its original magnetism or reduce its magnetization degree, and make the information stored in the magnetic stripe unreadable or damaged. However, the RFID chip in the ID card is not a magnetic material, so the ID card "demagnetization" is actually a false proposition and there is no need to worry about it.

Although the RFID chip of the ID card will not be "demagnetized", in some cases, the ID card may not be recognized normally. This is because the RFID chip of the ID card needs to communicate with the card reader contactlessly, and the card reader can only read the chip information within a certain distance range.

If the distance between the ID card and the card reader is too far or there are interference objects (such as metal), signal shielding materials, etc., the ID card will not be recognized. This is not because the ID card is demagnetized, but because the communication distance and interference factors make it impossible to read the chip information normally. In addition, if the chip in the ID card is damaged, it will also result in the inability to read the information. Therefore, when using the ID card, avoid twisting and high temperature to prevent the chip from being damaged.

Source: pixabay

The ID card also contains an induction antenna , which transmits radio waves when it is close to the reader/writer to complete the reading and writing operations of the chip data. However, factors such as extremely strong magnetic fields and radiation (such as X-ray machines in hospitals) may also cause abnormal charge movement in the coil, making the ID card unreadable in some cases, but this phenomenon does not mean demagnetization.

What will be demagnetized?

Because the chip in the ID card is made of special materials, it will not be demagnetized. However, some items will be demagnetized, first of all, magnetic storage media such as magnetic tapes and hard drives . The magnetic heads and magnetic media in these devices are easily affected when encountering strong magnetic fields, resulting in data corruption or unreadable data.

Bank card source: pixabay

The second is cards with magnetic stripes, including credit cards and bank cards. The magnetic stripes on these cards store key personal and financial information, and these magnetic strips are at risk of being demagnetized when they are close to strong magnetic fields.

In the past, non-smartphone speakers contained magnets with strong magnetism, so bank cards would be demagnetized. But today's smartphones have small speakers with relatively weak magnetism, and most of them are located at the bottom of the phone, so there is basically no need to worry about bank cards being demagnetized by the phone.

Magnetic stripe bank card source: pixabay

It should be noted that ID cards and other items may be required to be removed and inspected by X-ray or other detection methods when entering the security inspection machine. This is to ensure safety and prevent the carrying of dangerous and illegal items. According to security regulations, some items such as large-capacity liquids, flammable items, etc. cannot pass through the security inspection machine, and magnetic items such as large magnets, magnetic toys, etc. are not allowed to enter the security inspection machine.

Security inspection machine source丨Wikipedia/N509FZ

Security inspection machines mainly use technologies such as radiation or electromagnetic waves to scan and detect objects. When magnetic objects pass through the security inspection machine, they may interfere with the sensors and equipment of the security inspection machine due to their magnetism, affecting the normal operation of the security inspection machine. This may cause the security inspection machine to be unable to accurately identify other dangerous objects, thereby reducing safety.

Secondly, the strong magnetic field of magnetic objects may interfere with the electronic and magnetic components in the security inspection machine, causing equipment damage or malfunction. In order to protect the normal operation of the security inspection machine and extend its service life, it is usually stipulated that magnetic objects cannot pass through the security inspection machine.

In addition, magnetic items can easily interfere with other passengers' belongings when passing through security inspection machines. For example, luggage with magnetic items may affect or even damage other passengers' electronic devices.

Why can’t ID cards be “demagnetized” by mobile phones?

Based on the above analysis, we know that the ID card and the mobile phone will not be demagnetized when placed together, but the reason for this is that in addition to the chip in the ID card not being a magnetic material, there are two other influencing factors: frequency and intensity .

If the frequencies of the two radio waves are close, or the intensity of one radio wave is too strong and suppresses the weaker radio wave, then they are likely to interfere with each other, causing signal distortion or loss. However, if the frequencies of the two radio waves are very different, or the intensities of the radio waves are similar, they are unlikely to affect each other.

The frequencies of radio waves used by ID cards and mobile phones are very different. As for the intensity, the intensity of radio waves used by ID cards is very small and can only be effective within a distance of a few centimeters. The intensity of radio waves used by mobile phones is relatively large and can be effective within a distance of hundreds of meters or even kilometers. Therefore, if the mobile phone and ID card are far apart, they are unlikely to interfere with each other.

To sum up, the ID card and the mobile phone placed together will most likely not be "demagnetized". Interference is only likely to occur in the following two situations: the mobile phone and the ID card are very close and happen to be within the working range of the card reader, or the mobile phone is in a high-power state such as talking on the phone or surfing the Internet, and is close to the ID card. The radio waves emitted by the mobile phone may cause certain damage to the ID card chip, rendering the ID card invalid.

In short, in most cases, we don't have to worry about our ID cards being "demagnetized" when placed together with mobile phones. However, we still need to pay attention to the use of ID cards in daily life, and do not damage the chip inside to prevent ID cards from malfunctioning.