My weekends are usually spent working at Wegmans where people most often pay using a credit card. The new chip readers don’t always work and people always wish they could just go back to the old method of swiping. Interestingly enough, there is a significant amount of physics behind the simple swipe payment that I thought it might be interesting to explore.
To get a basic understanding of how a credit card works, you can think of the black strip on the back of the card as a strip of magnets placed in a specific pattern. When you swipe the card, the credit card machine’s coil of wires causes a change in the magnetic field. This is called electromagnetic induction. The change in magnetic field induces a voltage that creates a current that is used to signal your account information to the machine.
I never knew that all of this went on when someone swiped their card at Wegmans! I hope to learn more about this in the future when we start learning electricity and magnetism. For a more in-depth explanation of how a credit card works, visit this website: http://pages.vassar.edu/ltt/?p=965