Putting a coin on top of a running microwave oven can be extremely dangerous and should never be attempted. Here are the reasons why it is hazardous:
Fire Hazard: When a metal object, like a coin, is placed inside a microwave oven, it can cause a phenomenon known as "arcing." Microwaves are designed to heat food by emitting electromagnetic waves that excite water molecules in the food, generating heat. When metal is present, it reflects and concentrates the microwave energy, leading to electrical sparks or arcing. This can cause the coin to heat up rapidly and potentially catch fire, leading to a microwave oven fire.
Damage to the Microwave Oven: The arcing caused by the metal object can damage the interior of the microwave oven, including the oven's cavity, turntable, and magnetron (the component that generates microwaves). Repairing or replacing these parts can be costly.
Risk of Explosion: In extreme cases, if the coin has a pointed edge or shape and is left in the microwave for an extended period, it may become superheated and explode, posing a risk of injury to anyone nearby.
Electrical Hazards: Placing metal objects on top of a running microwave can also create electrical hazards. It may interfere with the microwave's proper functioning and could lead to electrical shorts or damage to the appliance.
Health Risks: If the coin does not immediately cause a fire or explosion, there is still a risk of harmful substances being released into the air if the coin melts or gives off toxic fumes.
For safety reasons, it is essential to never place any metal objects, including coins, inside a microwave oven or on top of it while it is running. Always follow the manufacturer's instructions and use only microwave-safe cookware and utensils when operating a microwave oven.