How Do Vending Machines Detect Fake Coins?

Narrator: WHEN YOU’RE HUNGRY, YOU NEVER QUITE HAVE THE RIGHT COINS FOR THE SNACK YOU WANT. HOW DOES THE MACHINE KNOW TO SEND BACK ANYTHING FAKE AND KEEP TRACK OF HOW MUCH YOU’VE PAID? THE MACHINE DECIPHERS COINS WITH PINPOINT ACCURACY. LIGHT SENSORS MEASURE THE SIZE, AND ELECTROMAGNETS DETECT THE METAL TYPE, IDENTIFYING THE COINS […]