2. This is mainly related to the heating method of the microwave oven. The microwave oven uses microwaves to heat food, but microwaves can only penetrate insulating materials such as glass, ceramics and plastics. For objects containing metal components such as steel, iron and tin, they will get hot and even burn in the microwave oven, so it is very dangerous to put metal objects in the microwave oven. Tin foil, on the other hand, is a metal material, which is conductive and has a reflective effect on microwave, causing sparks when microwave contacts with metal, which is dangerous and even damages the magnetron of microwave oven.