Microwave ovens have three characteristics: penetration, absorption and reflection. In the case of paper, porcelain and glass, ordinary microwaves will penetrate the utensils to heat food. Oscillating heating is carried out on water molecules and protein, sugar and other accumulated molecules in food, and microwave kinetic energy is converted into heat energy of food to absorb heat. Reflective metal. Therefore, metal utensils are generally not used as containers for holding food.

Microwave heating is heating by microwave exciting the natural vibration of water molecules in food, and the molecular movement is intensified. Therefore, only the food itself absorbs microwave and converts it into heat energy during heating. Microwave can't penetrate metal objects, but it will be reflected back. Microwave can penetrate non-metallic materials such as ceramics, plastics and glass. These materials won't absorb microwaves, so they won't be heated (which is why plastics won't melt when heated). Metals will also generate large current by absorbing microwaves to excite electron oscillation. Therefore, if food is put in a metal container and heated in a microwave oven, on the one hand, the microwave is blocked because of the shielding effect of metal, so that food cannot be heated; On the other hand, because the microwave excites the electrons in the metal, a large current discharge spark will be generated between the metal container and the furnace body, and the furnace body or the container will be burned seriously.

The furnace body is made of metal plate, and the inner side of the oven door glass (designed for easy observation) is equipped with a metal mesh, which is a protective layer set by using the shielding effect of metal on microwaves to prevent microwave leakage from harming human body.

The metal barbecue grill can be put in the stove. The principle is that the metal frame made of fine iron wire has a small reflection area and does not form a relatively closed container to shield microwave, so microwave can heat food. However, it should be noted that the metal frame must not touch the metal furnace wall, otherwise it will produce large current discharge and arc, which will burn out the microwave oven.

The following are the hazards of using metals:

1。 It is not conducive to rapid temperature rise. Because the microwave is reflected.

2。 There will be sparks. The reflected irregular electromagnetic wave collides with metal to produce sparks.

3。 Reduce the life of magnetron emission tube and the influence of electromagnetic echo on components.