Dielectric heating
http://en.wikipedia.org/wiki/Dielectric_heating
polar molecules like water having an electrical dipole, they align themselves in an electromagnetic field by rotating; as the field alternates in the form of a wave, the molecules reverse and oscillate with the electromagnetic wave. the heat generated is caused by the vibrational movement of the molecules i.e. kinetic energy.
http://en.wikipedia.org/wiki/Microwave_oven
the reason Microwave ovens work so fast is because they are very efficient.
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A typical consumer microwave oven consumes 1100 W of electricity in producing 700 W of microwave power, an efficiency of 64%
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and the energy that goes into heating say a cup of water goes into heating the water and not the cup.
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Cooking in conventional ovens entails heating the internal structure of the oven to cooking temperature and, additionally, it involves maintaining that temperature against convective and radiative losses of heat for a longer time than is usual with a microwave oven. The efficiencies of conventional cooking methods can be difficult to quantify but tend to be low.
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it is not accurate to say that microwave ovens heat from the inside out
http://www.straightdope.com/columns/...the-inside-out
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While microwave radiation does penetrate the surface of food and start to heat the inside at roughly the same time as the surface, it's not necessarily accurate to say the food is cooked from the inside out. Microwaves heat food by being absorbed primarily by liquid water molecules, and to a lesser extent fats and some sugars, imparting energy to them in the form of heat.
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http://en.wikipedia.org/wiki/Water_absorption
the absorption frequency of water is complex
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Strong water vapor absorption bands occur at wavelengths around 2500, 1950 and 1450 nanometers (nm),[1][2] with weaker absorption around 1200 and 970 nm,[3] and three additional sets of water-vapor absorption lines near 930, 820, and 730 nm,[4] all in the infrared spectrum.
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http://en.wikipedia.org/wiki/Microwave_oven
to paraphrase:
Microwave ovens work at usually at a frequency of 2.45 GHz (a wavelength of 12.24 cm)
which is the same as a WIFI wireless router
http://www.moonblinkwifi.com/2point4freq.cfm
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n the United States and Canada there are 11 channels available for use in the 802.11b 2.4GHz WiFi Frequency range. This standard is defined by the IEEE.
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