what is the working principle of the hot plate

What is the working principle of the hot  plate:

The heating plate is formed by a combination of a heating tube and a heat-conducting sheet. The heating source is generated by the heating tube inside the heating plate. The heating tube is a U-shaped high-temperature resistant seamless steel tube. The voids in the tube are filled with crystalline magnesium oxide powder with good thermal conductivity and insulation. There are ceramic insulating terminals in the two sections of the heating tube, and there are terminals in the middle. The surface of the heating tube is transmitted, and then conducts to the heat-conducting sheet of the heating plate and the pot body, and the food in the pot will be heated at this time. This structure has high thermal efficiency, rapid heating, uniform heating, and good stability. When the heating tube is electrified and heated, the magnesium powder is insulated, the surface of the heating tube is not charged, and the use is safe and reliable.