Heating media can generally be divided into

Nonpolar molecular dielectric and polar molecular dielectric

. When no electric field is applied, polar molecules do not show polarity. If this medium is placed in an external electric field, each polar molecule will form an orderly arrangement along the direction of electric field force, and the opposite charges will be induced on the surface of the medium, which is called polarization. The stronger the applied electric field, the stronger the polarization. When the applied electric field changes direction, polar molecules also form an ordered arrangement in the opposite direction. If alternating electric and magnetic fields are applied, polar molecules will be magnetized repeatedly. The higher the frequency of alternating electric field, the faster the polarization of polar molecules rotates repeatedly. At this time, the kinetic energy of molecular thermal motion increases, that is, the heat increases, and the temperature of food also increases, thus completing the transformation from electromagnetic energy to heat energy.