How Microwave Oven Works?
Likri
When we press the "start" button of a microwave oven we activate a powerful magnetic field, which oscillates in the same frequency band used for TV and radar transmissions, generated by a "cannon" that produces radio waves that will allow food to cook .
The microwaves fired from the oven influence the quiet state of the water molecules present in the food, making them vibrate up to 2,500 million times per second. Moving so quickly, these molecules overheat reaching very high temperatures that allow food to cook. In latest ovens, all energy is absorbed by food, which therefore cooks much more quickly and economically than traditional cooking methods.
Since microwaves act only on water molecules, the containers containing the food do not heat up since they do not absorb energy from the magnetic field created in the oven. Of course part of the heat of the food spreads to the containers, which are therefore equally hot at the end of cooking. In a microwave oven, containers made of porcelain, glass, paper or a particular plastic resistant to high temperatures can be used. On the other hand, it is not advisable to use metal containers and aluminum foil which, reflecting the microwaves, do not allow homogeneous cooking of the food and in some cases can also damage the "magnetic cannon" of the oven.
The radio waves commonly used for the transmission of data, or of voice and music, have a length that can vary from a few meters to thousands of meters. As the word suggests, microwaves are very short and reach an average length of 12cm . An electromagnetic wave is a particular vibration of electric and magnetic fields, which constantly moves (ie oscillates) from negative values to positive values. Microwave ovens use waves characterized by a number of 2,450 million cycles per second (i.e. they oscillate 2,450 million times from a positive value to a negative value per second). Their frequency is therefore 2,450 megahertz (MHz).
Simplifying a lot, we can say that the water molecules on which the waves act have one end with a positive charge and one with a negative charge. By oscillating between a "plus" and "minus" value, microwaves interact with water molecules attracting and rejecting them millions of times per second . In doing so, the molecules move swirling in alternate directions, at a frequency of 2,450 million times per second, overheating from the friction and the very high speed reached.