How Microwave Ovens Work

A magnetron vacuum tube is the engine behind the way a microwave oven works. This converts electrical energy into high frequency electromagnetic waves, called microwaves. The microwaves then go in to the oven cavity through a wave guide and distributed fairly evenly by a fan.

There are three possible results for these waves.

They are either reflected back in, or they pass through or are absorbed by materials. These types are reflected back back by a metal. This is why non metallic utensils should be used in a microwave. Glass, china, paper, pottery, and a lot of plastics permit them to pass through. They because of that make ideal cooking utensils. The fat, water, and other substances in the food absorb them, leading the molecules to vibrate very fastmillions of times each second, actually. The name for this is dielectric heating. The molecules of many substances (including water) have a positive electric charge at one end and a negative one at the other. They therefore alternate very quickly as they try to get in line with the alternating electric field of the microwaves. This process is more effective} on water than on fats, and also works well on frozen water. The energy produced then cooks the food. This can be compared to rubbing pieces of wood together to make a flame. It is often believed that microwave cookers cook from the inside first. This isn’t the case.
Then, depending on the water composition, microwaves rapidly enter a distance into the food. However conventional cooking will only have an immediate effect on the outside of food.
This way is clearly different to conventional cooking, where energy is passed along a number of molecules until the food is completely hot and then gets cooked. Microwave dishes remain much cooler and timings are significantly reduced.
Another type is the convection or combination microwave. They are ideal for cooking prepared dishes, particularly if browning is desirable. Many will recent types have a high power quartz halogen bulb which aids quick browning. It is also possible that an accessory browning tray is used manufactured of porcelain or glass. This permits the top layer of food to become oxidised until it changes to brown.
Microwave models have much the same design. Microwaves have a cabinet, a wave guide, magnetron vacuum tube, wave stirrer, controls, and power cord and supply. Many also have extra features such as automatic defrost, variable power settings, a turntable, an integral thermometer, or a browning feature.
There is metal lining inside the walls and bottom, which stops the microwaves from escaping , and reflects them back to ensure the food is cooked. The frame and door have specially made seals that is designed to ensure that the microwaves remain in. Also there will be a device that makes sure that the microwaves will not continue whenever the door is opened. The door itself is usually a transparent panel for easy viewing, with a conductive mesh layer to keep a barrier. The hole diameters in the mesh is less than the wavelength of the microwaves, so the radiation can’t get past the door. Whereas light (with a much shorter wavelength, can get through.
Several makes microwave types allowseveral levels of power to be used, usually with a defrosting level. In most cases this will not mean that the magnitude of the microwaves varies - just that the waves switched on and off at particular regular periods.