Microwave Ovens

• Microwave ovens use electromagnets to give off microwaves. These waves cause fat and water molecules to vibrate. As these molecules vibrate, they rub against one another, giving off heat. Exposure to the microwaves cooks food items over time. Microwave ovens often cook food more quickly than conventional ovens because the use of microwaves speeds up the cooking process. The microwave oven itself is a gigantic electromagnet -- the microwaves resonate throughout the oven when it is in use.
  
  

Radiation

• Technically speaking, microwave ovens use radiation to cook food. However, these types of electromagnetic waves are not as powerful as the radiation used in X-rays or in cancer treatments. Microwave ovens use non-ionizing radiation waves; these waves are far less powerful and can't penetrate cells or destroy living tissue. Microwaving food is safe, while taking an X-ray of the same food items might not be as safe.
  
  

Uneven Cooking

• Microwave ovens do not warm everything equally the way a conventional oven does. This is because the electromagnetic waves cause water to vibrate, producing friction that generates heat and warms the food. If an item such as a tray doesn't contain a significant amount of water, the microwaves won't affect the tray. That's why trays will generally not be as hot as the food after cooking it in a microwave oven. If food cells contain uneven amounts of water, some of the food will get hotter than the rest.
  
  

Toasters

• Electromagnets are also used in toasters to help toast the bread. The electromagnet doesn't help warm the toast -- it ensures that the handle stays down until the toast is ready. When you push the toaster handle down, it activates a small electromagnet, which pulls the handle towards a metal piece and keeps it from popping back up. When a timer inside the toaster goes off, the electromagnet turns itself off and the toast pops back up.