How does Mirco Wave Oven work ?? ( Explain in English )

Microwave used in domestic oven is electromagnetic waves of frequency 2.45 GHz, which is produced by a mangetron.

Foods contains much water. The water molecules are in the form of dipoles (i.e. molecules having positve charge at one end and negative chrage at the other end). When microwave incidents onto water molcules, the molecular dipoles are affected by the rapidly changing electric field component of the microwave. They tend to follow the oscillation of the changing electric field to oscillate themselves very rapidly. These drastic oscillation of water molecules increases the collisions between neigbouring molecules, thus resulting in heat production, which heats up the food.

Since heating by microwave depends on the oscillation of water molecules, substances contain plenty of water would be heated up more effectively by microwave. Substances with little or no water, eg. glassware, would not get hot even placed in an microwave oven in cooking.

The following web-page gives more details on how microwave works in an oven:

http://en.wikipedia.org/wiki/Microwave_oven

microwave oven will emit microwave with frequency similar
to that of water molecules. when the water molecules in the
food absorb energy from the microwave, it will vibrate faster
and faster. the temperature will rise higher and higher.
so the food will get hot at last.