Microwave oven

A frequency of 2.45 GHz is used for heating food in microwave ovens in homes. An electromagnetic field with similar frequencies is also used for mobile telephony (UMTS) and in WiFi devices, but in this case with much lower energy (by a factor of approximately 4,000). In the oven, the microwaves are absorbed by the food where they excite molecules (particularly water molecules) to oscillate. The resulting frictional energy heats up the food. The electromagnetic field doesn’t leave the cooking chamber. To the outside it is shielded with metal sheets and grids, also in the area of the viewing window. For safety reasons, the power supply is automatically switched off when opening the door. Under normal conditions, leakage radiation can escape only to a very small extent. If this is the case, it would be close to the door crack. In the case of a defective or heavily soiled door seal, increased radiation leakage is likely to occur. Generally, a few centimeters away from the window and the door crack the safety limits are adhered to.

Typical measurement values are available in the database of exposure sources.
Usual microwave oven
photo: Hedwig von Ebbel, license: public domain, via Wikimedia Commons