Microwaves, like visible light, are a part of the electromagnetic spectrum and are extremely high frequency radio waves. Microwaves travel in straight lines and may be reflected, transmitted or absorbed by matter in their path. Metallic materials totally reflect microwaves. Non-metallic materials such as glass and plastics are partially transparent to microwaves.
Materials containing moisture such as foods absorb microwave energy and produce heat.
Some of the more common uses of microwaves include satellite communications, radar, car phones, air and navigational aids. Other applications include use in industry for thawing and drying materials and in medicine in diathermy treatment as well as household use for the preparation of food. In the microwave oven an electronic tube called a magnetron is used to produce the microwaves. The magnetron, basically coverts 60 Hz power line electric current to electromagnetic radiation at 2450 MHz. The microwave then pass through a wave guide into the metal oven cavity where they are reflected around the oven walls.