Microwave oven

A microwave oven is a kitchen appliance employing microwave radiation primarily to cook or heat food.

Description

A microwave oven consists of:

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• a magnetron,
• a magnetron control circuit (usually with a microcontroller),
• a waveguide, and
• a cooking chamber

A microwave oven works by passing microwave radiation, usually at a frequency of 2450 MHz (a wavelength of 12.24 cm), through the food. Water, fat, and sugar molecules in the food absorb energy from the microwave beam in a process called dielectric heating. Most molecules are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other, and are therefore twisted to and fro as they try to align themselves with the alternating electric field induced by the microwave beam. This molecular movement creates heat. Microwave heating is most efficient on liquid water, and much less so on fats, sugars, and frozen water. Microwave heating is sometimes incorrectly explained as resonance of water molecules, but this occurs only at much higher frequencies, in the tens of gigahertz.

Related Topics:
Radiation - Frequency - MHz - Wavelength - Cm - Water - Fat - Sugar - Molecule - Energy - Dielectric heating - Dipole - Heat - Resonance - Giga

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The cooking chamber itself is a Faraday cage enclosure to prevent the microwaves escaping into the surroundings. The oven door is usually a glass panel for easy viewing, but has a layer of conductive mesh to maintain the shielding. Since the mesh width is much less than the wavelength of 12 cm, the microwave radiation can not pass through the door, while visible light (with a much shorter wavelength) can.

Related Topics:
Faraday cage - Wavelength - Light

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Professional chefs generally find microwave ovens to be of limited usefulness. See Microwaving for a discussion of this reason.

Related Topics:
Chef - Microwaving

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With wireless computer networks gaining in popularity, microwave interference has become a concern among those with wireless networks. Microwave ovens are capable of disrupting wireless network transmissions due to the fact that the microwave creates radio waves at about 2450 MHz. This is about the same frequency that wireless networks use, so microwave ovens in use can interfere with network signals and cause connection issues.

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