Dielectric heating (also known as electronic heating, RF heating, high-frequency heating) is the phenomenon in which radiowave or microwave electromagnetic radiation heats a dielectric material, especially as caused by dipole rotation. For other uses, see Radio (disambiguation). ... This article is about the type of Electromagnetic radiation. ... This box:      Electromagnetic (EM) radiation is a self-propagating wave in space with electric and magnetic components. ... A dielectric is a physical model commonly used to describe how an electric field behaves inside a material. ...

There are two principal mechanisms by which a non-conductive material can be warmed in an EM field:

1. Electrical conduction: current flow in the oscillating electric field allows the material to absorb energy as heat. Since current flow implies that the material is not an electrical insulator this is rarely considered true dielectric heating.
2. Dipole rotation: Molecular rotation occurs in materials containing polar molecules having an electrical dipole moment, which will align themselves in the field by rotating; as the field alternates, the molecules reverse direction and accelerate the motion of individual molecules or atoms. Heat is a form of energy possessed by a substance by virtue of the vibrational movement, i.e. kinetic energy, of its molecules or atoms.

Dipole rotation is the mechanism normally referred to as dielectric heating, and is most widely observable in the microwave oven where it operates most efficiently on liquid water, and much less so on fats, sugars, and frozen water. The reason is that fats and sugars are far less polar than water molecules, and are thus less affected by the forces generated by the alternating electromagnetic fields. Meanwhile, frozen water molecules are fixed in place in a crystal lattice, and cannot freely rotate and absorb heat from molecular friction. Outside of cooking, the effect can be used to heat solids, liquids, or gases (see states of matter). Conduction is the movement of electrically charged particles through a transmission medium (electrical conductor). ... This article or section is in need of attention from an expert on the subject. ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... This article is about rotation as a movement of a physical body. ... A commonly-used example of a polar compound is water (H2O). ... In physics, the electric dipole moment is a measure of the polarity of a system of electric charges. ... City lights viewed in a motion blurred exposure. ... Microwave oven A microwave oven, or microwave, is a kitchen appliance employing microwave radiation primarily to cook or heat food. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... For other uses, see FAT. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... This article is about sugar as food and as an important and widely traded commodity. ... In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ...

Communication microwave frequencies penetrate semi-solid substances like meat, and living tissue to a distance proportional to its power density. Some environmentalists are concerned that the widespread adoption of microwave-emitting mobile phones could harm human and animal health through dielectric heating. For the Bobby Womack album, see Communication (1972 album). ... This article is about the food. ...

References

• Metaxas, A. C. (1996). Foundations of Electroheat, A Unified Approach. ISBN 0-471-95644-9.