When you go out far away, if you have food frozen in the refrigerator, you can put a coin, and that's why.
First, the refrigerator may lose power. In life, if you go out for a long time and the refrigerator at home has frozen food, you must consider the situation that the refrigerator is powered off. The refrigerator has a short power outage time and may only affect the appearance of the frozen food; A prolonged power outage may affect the quality of frozen food.
Secondly, the coin recognizes the power off. When you go out, fill a bowl or cup with water, first freeze it in the freezer box of the refrigerator to freeze into ice cubes, and then place a coin on top of the ice cube to mark the coin location. When you come back, open the freezer in your fridge and check where the coins are. If the coin position is lowered, it means that the refrigerator at home has been powered out and the ice has melted. The lower the coin position, the longer the refrigerator will be powered off.
Third, judge food trade-offs. The food in the refrigerator may have thawed due to a power outage, frozen due to an incoming call, the surface has not changed, and the inside has deteriorated. When you go out for a long time, you can't tell if the refrigerator has been blacked out, let alone whether the food has spoiled, so you need to look at the coin. If the refrigerator has a power outage, the ice frozen in the container will melt, and the water in the container will be lowered due to evaporation, and the coin position will be lowered, and the lower the coin position, the longer the refrigerator will be blackout, and the more likely the food will spoil. So, if the position of the coin remains the same or changes slightly, the refrigerator food can be eaten with confidence; If the coin is low or has reached the bottom, it is best to discard the food in the refrigerator.