Microwaves cook food using the heating effect of high-frequency radio waves. The oven produces these "microwaves" at intervals during the cooking process - the number and length of the pauses is dictated by the power level you choose.
Cooking time and power level are set using the control panel. Your oven may also have presets for common tasks like defrosting and reheating.
230V mains power supply passes through safety systems designed to cut the power in the event of overheating or the door being opened.
The mains voltage is stepped up by a transformer and a capacitor to around 3000V, to power the magnetron, which generates the microwaves.
Microwaves are conducted through the wave guide into the cooking chamber. Here they are reflected from the walls and door, and penetrate the food from the sides and above.
A turntable rotates the food slowly to give even cooking. Some ovens achieve this by using a microwave stirrer instead. This is positioned inside the roof of the chamber.
How microwaves cook food
Microwave ovens use high-frequency radio waves (microwaves), oscillating at approximately 2.5GHz, to cook your food. At this frequency microwaves are absorbed by water, certain fats and sugars - the primary constituents of most foods.
- In a water molecule, the two hydrogen atoms (shown in red) carry a small positive charge, and the oxygen atom (blue) carries a negative charge.
- The oscillating electric field of the microwave interacts with these charged atoms to cause the molecule to twist. This rotation causes friction, producing heat to cook food or boil fluids.