How is it possible to activate a credit card by tapping it against one’s phone?

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How is it possible to activate a credit card by tapping it against one’s phone?

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Modern contactless cards have microchips embedded inside them that gives off unique signals. But in order for that to work, the opposite technology has to exist (the ability to read and interpret the signals given off by a credit card). It used to be that only card readers like you see in stores had that reading technology, but now some phones have it as well. So basically, credit cards emit signals and phones can read those signals and interpret it

The card chips is powered by the reader. Basically, the reader sends a “power-up” signal which the chip uses to execute whatever program there is on the chip. This is called a contactless smart cards.

Embedded in the plastic around the card’s chip is a thin, coiled, foil radio antenna. The antenna’s length makes it resonant for the radio frequency at which the RFID reader operates. The radio signal itself induces enough current in the antenna to operate the chip, which replies to the RFID signal with its own radio transmission that supply’s the card’s information.

The low power of the card’s reply signal means the card needs to be right next to the reader.

The most reliable way to tap a card is with the chip near your hand, placing the antenna right over the card reader.