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A microwave oven or simply microwave is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. [1] This induces polar molecules in the food to rotate and produce thermal energy in a process known as dielectric heating .
Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequencies between 300 MHz and 300 GHz, broadly construed.
This patent proposed radio frequency (RF) heating at 10 to 20 megahertz (wavelength 15 to 30 meters). [7] Such wavelengths were far longer than the cavity used, and thus made use of near-field effects and not electromagnetic waves. (Commercial microwave ovens use wavelengths only 1% as long.)
The higher energy (shortest wavelength) ranges of UV (called "vacuum UV") are absorbed by nitrogen and, at longer wavelengths, by simple diatomic oxygen in the air. Most of the UV in the mid-range of energy is blocked by the ozone layer, which absorbs strongly in the important 200–315 nm range, the lower energy part of which is too long for ...
Susceptors meant to heat foods by direct conduction may be seen in the gray lining of packaging directly holding the food, and generally in good contact with it. For this reason, products meant to be browned via susceptor-generated thermal radiation carry instructions to microwave the food while still inside its packaging.
Microwave is a term used to identify electromagnetic waves above 10 3 megahertz (1 Gigahertz) up to 300 Gigahertz because of the short physical wavelengths of these frequencies. Short wavelength energy offers distinct advantages in many applications. For instance, sufficient directivity can be obtained using relatively small antennas and low ...
L e,Ω,λ is the spectral radiance in wavelength of that surface; L e,Ω,λ ° is the spectral radiance in wavelength of a black body at the same temperature as that surface. Hemispherical emissivity can also be expressed as a weighted average of the directional spectral emissivities as described in textbooks on "radiative heat transfer". [12]
Microwave chemistry is the science of applying microwave radiation to chemical reactions. [1] [2] [3] [4] [5] Microwaves act as high frequency electric fields and ...