What technique is used in microwave ovens to cook food in minutes?

Microwave ovens have provided the mankind with the whole new way of cooking, quite unlike the conventional method followed since thousands of years. When cooking is done in a customary manner, the heat that comes from a conventional gas stove is transferred to food by conduction. The heat is passed first to the food’s outer layers and then progressively to its inner ones. But microwave ovens produce heat directly inside the food, heating it more evenly and more quickly than gas stove.

Let’s see how this works. Inside the microwave oven, a device called magnetron generates the microwaves which are fields of electrical and magnetic energy. These are directed by an antenna to a hollow tube called waveguide. The tube in turn channels the waves to a fanlike stirrer that disperses them around the oven’s interior. Finally, the waves reflect off the oven’s walls and are absorbed by water molecules in the food.

It is the water that plays key role in cooking. Each molecule of water has a slight positive charge at one end and a slight negative charge at the other. The molecules lie randomly in the food. But as they absorb the microwaves, they align themselves with the waves’ electric field. The electric field oscillates billions of times a second, constantly agitating the water molecules and forcing them to turn round 180° as many times.

In other words, as the microwaves oscillate, so do the molecules. This rapid molecular agitation generates heat and cooks the food. If the food is very thick, the microwaves will not penetrate completely and the food’s inner layers will cook by conduction. Since microwaves don’t produce heat unless they are absorbed by water molecules, many materials such as glass, paper and most plastics can be used safely as cookware.

Which brings us to another question, are microwaves safe? People are often afraid to stand close to the microwave. Even though it is a wise decision, but it is not going to cause you to harm anyways. The reason being that the cooking cavities of a microwave are basically metal containers that are tightly sealed. If you closely observe the glass door inside, you will find out that there is a metal grid stuck to the back. If you are thinking about the holes, they are too small to let the microwaves pass through.

Another safety feature that microwaves include is the magnetron, which stops buzzing as soon as you open the door. Most microwaves have two interlocks that are independent in case if one of them fails. Microwaves are tested thoroughly before they are rolled out for production. You cannot expect them to develop leaks anytime soon until and unless they are not properly maintained or if the metal grid in the back develops rust. Even if your microwave happens to be leaking, it will not cause much harm. Although microwaves are capable of producing very high power inside, it starts to drop quickly as you go up further.

Incase if a microwave is leaking, the electromagnetic waves at a few distances will not have a negative effect, as the radiation is as tiny as you would pick up from your cellphone.

Another concern shared by people is that microwave tends to rob foods off their nutritional value. It has indeed proven to be the exact opposite. It is a well-known fact that cooking at a higher temperature does reduce nutrients in foods, but that is not the case with microwaves. The extent of damage depends on the temperature and the length of cooking time. In the case of microwaves, since both the temperature and cooking time is comparatively less, it is less likely that any damage will be done. However, if you choose to cook your food up to a boiling point, that could be harmful either on a stove or in a microwave.