In recent decades, the use of microwave ovens has become widespread. These devices apply the principles of dielectric heating. Molecules such as the water within food will generate heat when placed within a high-frequency electric field. Microwave ovens are thus used for cooking, thawing, and reheating. Despite their utility though, the ovens have also been associated with certain safety problems. Excessive radiation leakage, for example, represents a potential health hazard. However, such risks have been practically eliminated through adequate safety standards and good oven design.
The principles of dielectric heating were first applied to industrial uses during the late 1930s (2:401-402). Then during World War II the electronics company, Raytheon, began mass-producing small microwave transmitters called magnetrons. Although these power sources were initially used in radar, they were soon considered for other purposes. By 1952, Raytheon researcher, Percy Spencer, had a patent for a microwave oven. While this first oven "stood as tall as a man," subsequent innovation led to dramatic design improvement (7:54-60). Microwave ovens are currently produced by several different countries for a variety of purposes. In 1991, Andrews estimated world-wide production at roughly 30 million per year (4:102-108). According to Roman (1989) there are over 60 million microwave ovens in American homes alone (7:54-60).
Perhaps the most important component of the microwave oven is its magnetron. These power sources have not changed much since World War II. Acting as simple particle accelerators, magnetrons consist of a vacuum tube containing an electron-coated wire. When the wire is charged with electricity, the electrons begin to "swarm around the tube like angry bees (7:54-60)." This activity ultimately generates electromagnetic waves of various wavelengths and frequencies. However, a dimpled metal strip within the magnetr...