Microwave oven, coloured X-ray. Microwave oven cooking food in a bowl. The food sits on a glass plate (bottom centre) that turns slowly as the microwave cooks. The oven's door with its protective mesh (centre, grey) and the control pad (upper right) can be seen. The magnetron (purple, lower right) is a microwave tube in which electrons are generated from a heated cathode. These are affected by magnetic and electric fields to produce the microwaves (radiation). The microwaves are directed onto the food, which make water and fat in the food vibrate, heating it.