@nippon.brief: When a passenger taps a transit IC card at a station ticket gate, how does the gate decide in an instant to let them through? The card holds no battery, and inside it are only a coil and an IC chip. The ticket gate is always sending radio waves at 13.56 megahertz, even while no card is there. When the card enters those radio waves, a current arises in the coil, and that power starts up the IC chip. But if only the ticket gate confirms the card, a fake gate could take the balance from the card. So before any balance moves, the ticket gate and the card check that each of them is genuine. The gate takes the balance only from a partner that passed the check, subtracts the fare, and sends the balance back. But if the exchange had to reach a distant server, the handling would take time. So the gate sends the fare-deducted balance to the card, and the IC chip inside the card writes that updated balance itself. That is why a passenger can pass through the ticket gate in an instant after tapping: the gate's radio waves start up the card, and the check and the balance update both finish right there. Sources: Sony, "How FeliCa works"; Sony, "What is FeliCa"; Wikipedia, "FeliCa"; Impress Watch, on the speed difference between Suica and Visa contactless payment at ticket gates Narration: Kokoro (af_heart) #iccard #ticketgate #nfc #howitworks #everydayscience

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Friday 18 September 2026 00:00:00 GMT