Certain items, however, such as grease, bones, corn husks, and paper, can damage the disposal unit. The garbage grinder is fitted into a sink drain so that, with a continuous flow of cold water, the waste may be flushed into the sewage system as it is ground. The unit contains steel knives that rotate at high speed inside the food-waste container. The motor is started by an electric switch near the sink or by an internal switch that is tripped by the flow of cold water. Microwave ovens convert electric energy into microwave energy to heat or cook foods quickly.
Electricity passes through a magnetron tube to produce microwaves.
The microwaves are then channeled to a slow rotating fan, which distributes them into a metal oven cavity. The waves bounce off the top, bottom, and sides of the cavity to penetrate the food evenly. Outdoor grills may also be included among larger kitchen appliances. Electrically heated devices are based on the fact that as electricity flows through a substance, the resistance offered by the material creates heat. The amount of resistance depends on the material used.