How do microwave ovens work ?

Microwave ovens have become and indispensable part of our kitchen.  These useful appliances are able to heat and cook food quickly and efficiently.  They are compact and clean. 

Microwaves work by heating the food with microwaves.  Microwaves are waves which are situated between the infrared and radar waves in the electromagnetic spectrum.  microwave

The microwaves are generated by a device called a magnetron.  The magnetron generates the microwaves at a frequency of 2.45 GHz and a wavelength of 12.2 cms.  The waves generated by the magnetron are focused at the food by means of a waveguide. 

The magnetron is powered by a high voltage transformer.  A microprocessor controls the entire process while a fan cools the components.

The Microwave oven works on the principle of dielectric heating.  A dielectric is a material which can be polarized.  All food materials contain water.  The water molecule has charge.  When it is placed in an alternating electric field, the molecule moves back and forth as the direction of the electric field changes. 

This produces heat which cooks the food. 

The food is placed in a cooking chamber,  The chamber is enclosed in a metallic cage which forms a faraday cage.  This is to ensure that the radiation does not come out. 

Microwave cooking is efficient as the food alone gets heated.  The heating is uniform, unlike conventional cooking where the heat travels from the outer surface of the food to the inner parts.  This eliminate localized overcooking. 

Microwave cooks at a lower temperature.  This prevents the formation of tars and char in the food.