How do Microwave Ovens Work?

A magnetron vacuum is the engine behind a microwave oven. Electrical energy is converted into microwaves, a high frequency type of wave. The microwaves then go in to the microwave through a wave guide and stirred by a fan to be distributed evenly.

These waves are then reflected, pass through materials or are absorbed by other materials. These types are reflected back by a metal. This is why non metallic utensils should be used in a microwave. Glass, china, pottery, paper, and a lot of plastics allow them to pass through. They therefore make perfect cooking utensils. The fat, water, and other materials in the food absorb them, leading the molecules to vibrate very fastmillions of times each second, actually. The name for this is dielectric heating. Many molecules (including water) have a negative charge at one end and positive one at the other. They as a consequence rotate very rapidly as they try to get lined up with the alternating electric field of the microwaves. This method is more effective} on liquid water than on other food materials, and also works well on frozen water. The heat produced thus cooks the food. This can be compared to rubbing sticks together to make a fire. It is widely believed that microwave cookers cook from the inside out. This is not the case.
What happens is that, depending on the water content, microwaves rapidly penetrate several centimetres into the food. On the other hand conventional cooking will only have an immediate effect on the outside of food.
This method is obviously different to conventional cooking, where energy is passed along a length of molecules until the food is completely hot and thus gets cooked. Microwave dishes remain less hot and timings are greatly reduced.
A variant is the convection or combination microwave. They are ideal for cooking prepared dishes, particularly if browning is wanted. Many recent types have a high power halogen bulb which aids rapid browning. It is also possible that an accessory browning tray is used made of porcelain or glass. This allows the outside layer of food to be oxidised until it changes to brown.
All microwave models have much the same design. They have a cabinet, a magnetron vacuum tube, a wave guide, wave stirrer, controls, and power cord and supply. Many also have extra features such as automatic defrost, variable power, a turntable, a built in thermometer, or browning elements.
There is metal lining inside the walls and base, which stops the microwaves from getting out , and reflects them back to ensure everything is thoroughly cooked. The frame have specially made seals that is designed to make sure that the microwaves remain in. Also there will be a device that ensures that the microwaves will stop whenever the door is not closed. The door itself is usually a transparent panel for good visibility, with a layer of conductive mesh to maintain a barrier. The hole sizes in the mesh is smaller than the wavelength of the microwaves, so the radiation can’t escape from the door. Whereas light (with a much shorter wavelength, can make it through.
Many types allow several levels of power to be chosen, often with a power level that defrosts. Usually this doesn’t mean that the magnitude of the microwaves differs - just that they’re switched on and off at certain regular intervals.