Microwave ovens can pass through insulating materials such as glass, ceramics and plastics by using microwaves, but will not consume energy; For food containing water, microwave can't penetrate, but its energy will be absorbed. The shell of the microwave oven is made of metal materials such as stainless steel, which can prevent the microwave from escaping from the oven, so as not to affect people's health. Food containers are made of insulating materials. The heart of microwave oven is magnetron. This electron tube, called magnetron, is a microwave generator, which can generate microwaves with a vibration frequency of 2.45 billion times per second. This invisible microwave can penetrate the food to a depth of 5 cm and make the water molecules in the food move with it. Intense exercise produces a lot of heat energy, so the food is cooked.