Why do you need to put coins in the refrigerator when traveling?

The specific method is to put a glass of water in the refrigerator to freeze before going out, and then put a coin on the ice.

In this way, if the refrigerator encounters a power outage, the ice cubes in the cup will melt and the coins will sink. If the freezer is cooled intermittently, the water inside will It freezes and melts repeatedly, but once the coin sinks it cannot rise.

The term "putting coins" here refers to taking a cup filled with water and placing a coin after the water in the cup freezes. If your refrigerator loses power while you're away, you can tell how long the outage lasted by how deep the coin dropped into the cup. If there is only a short power outage, the previous ice cube will not melt completely and the coin will only drop a little. If the power is out for a long time, the water in the cup will completely melt and the coins will sink to the bottom of the cup. Through this phenomenon, we can determine whether the food in the refrigerator has deteriorated after being out of power for a long time.