Microwave ovens use micro waves (or radio waves) to create oscillating electric fields in the food, causing the positively charged hydrogen atoms in the water molecules to rotate and become excited. This excitation causes friction in all of the molecules in the food, and thus, heat, which is used to cook the food. This process differs from that of a conventional oven, which uses heat transfer via convection, rather than electromagnetic waves, to cook food. In addition to this technology, microwave ovens implement a feature called a “defroster,” whose purpose is to cook frozen foods more effectively. The defroster works by heating the food on the outside first, rather than heating it altogether as a whole, so as to allow the outside to assist in heating the inside of the food.
In comparison to a conventional oven or rotisserie, the microwave oven has several advantages: First, it uses electromagnetic waves to cook food evenly, whereas a conventional oven starts heating from the outside toward the inside. This allows for greater cooking speed. Second, it saves energy by cooking only the food and not any other objects in the surroundings, since only the food has the necessary water molecules for the microwave’s heating procedure. The microwave oven has several disadvantages as well: One is that it cannot bake or brown foods, since all areas of the food are heated evenly. Another disadvantage is that it diminishes the nutrient and vitamin content in some foods, such as vegetables, due to radiation.